diff --git a/lfs.c b/lfs.c
index 47394faf..8489727c 100644
--- a/lfs.c
+++ b/lfs.c
@@ -543,6 +543,10 @@ static inline void lfs_rtag_untrim(lfs_rtag_t alt,
     }
 }
 
+static inline lfs_rtag_t lfs_rtag_inc(lfs_rtag_t tag) {
+    return tag + 0x8;
+}
+
 static inline lfs_rtag_t lfs_rtag_red(lfs_rtag_t tag) {
     return tag | 0x1;
 }
@@ -1158,6 +1162,7 @@ static int lfs_rbyd_fetch(lfs_t *lfs,
 
 static lfs_srtag_t lfs_rbyd_lookup(lfs_t *lfs, const lfs_rbyd_t *rbyd,
         lfs_rtag_t tag, lfs_off_t *off, lfs_size_t *size) {
+    printf("lookup(%08x)\n", tag);
     // no trunk yet?
     lfs_off_t branch = rbyd->trunk;
     if (!branch) {
@@ -1382,6 +1387,7 @@ static void lfs_rbyd_p_red(
 
 static int lfs_rbyd_commit(lfs_t *lfs, lfs_rbyd_t *rbyd,
         const struct lfs_rattr *attrs) {
+    printf("commit()\n");
     LFS_ASSERT(rbyd->erased);
 
     // setup commit state
diff --git a/tests/test_rbyd.toml b/tests/test_rbyd.toml
index 4f52c6c4..a06aa4fa 100644
--- a/tests/test_rbyd.toml
+++ b/tests/test_rbyd.toml
@@ -4,7 +4,7 @@
 # test with a number of different erase values
 defines.ERASE_VALUE = [0xff, 0x00, 0x1b, -1]
 
-[cases.test_rbyd_commit_fetch]
+[cases.test_rbyd_fetch]
 in = 'lfs.c'
 code = '''
     lfs_t lfs;
@@ -38,12 +38,11 @@ code = '''
     lfs_bd_erase(&lfs, rbyd.block) => 0;
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
-            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            NULL))) => 0;
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4, NULL))) => 0;
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
 '''
 
-[cases.test_rbyd_multi_commit_fetch]
+[cases.test_rbyd_multi_fetch]
 in = 'lfs.c'
 code = '''
     lfs_t lfs;
@@ -83,7 +82,10 @@ code = '''
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
 '''
 
-[cases.test_rbyd_commit_lookup]
+# [cases.test_rbyd_fetchmatch]
+# [cases.test_rbyd_multi_fetchmatch]
+
+[cases.test_rbyd_lookup]
 in = 'lfs.c'
 code = '''
     lfs_t lfs;
@@ -144,8 +146,7 @@ code = '''
     lfs_bd_erase(&lfs, rbyd.block) => 0;
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
-            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            NULL))) => 0;
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4, NULL))) => 0;
 
     lfs_rbyd_lookup(&lfs, &rbyd, 0, &off, &size)
             => LFS_MKRTAG(GSTATE, 1, 0);
@@ -167,7 +168,7 @@ code = '''
             => LFS_ERR_NOENT;
 '''
 
-[cases.test_rbyd_multi_commit_lookup]
+[cases.test_rbyd_multi_lookup]
 in = 'lfs.c'
 code = '''
     lfs_t lfs;
@@ -251,8 +252,95 @@ code = '''
             => LFS_ERR_NOENT;
 '''
 
-# [cases.test_rbyd_commit_fetchmatch]
-# [cases.test_rbyd_multi_commit_fetchmatch]
+[cases.test_rbyd_traverse]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_init(&lfs, cfg) => 0;
+
+    lfs_rbyd_t rbyd_init = {
+        .block = 0,
+        .trunk = 0,
+        .noff = 0,
+        .rev = 1,
+        .crc = 0,
+        .count = 0,
+        .erased = true,
+    };
+
+    // traverse requires correct biasing of the weights in the rbyd tree
+    // so that lookups return strictly the tag greater than or equal to
+    // the tag requested
+    lfs_rbyd_t rbyd = rbyd_init;
+    rbyd = rbyd_init;
+    lfs_bd_erase(&lfs, rbyd.block) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4, NULL))) => 0;
+
+    lfs_off_t off;
+    lfs_size_t size;
+    lfs_srtag_t tag = lfs_rbyd_lookup(&lfs, &rbyd, 0, &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 1, 0));
+    // TODO use lfs_tag_incid?
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 2, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_ERR_NOENT);
+
+    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, 0, &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 1, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 2, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_ERR_NOENT);
+'''
+
+[cases.test_rbyd_multi_traverse]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_init(&lfs, cfg) => 0;
+
+    lfs_rbyd_t rbyd_init = {
+        .block = 0,
+        .trunk = 0,
+        .noff = 0,
+        .rev = 1,
+        .crc = 0,
+        .count = 0,
+        .erased = true,
+    };
+
+    // traverse requires correct biasing of the weights in the rbyd tree
+    // so that lookups return strictly the tag greater than or equal to
+    // the tag requested
+    lfs_rbyd_t rbyd = rbyd_init;
+    rbyd = rbyd_init;
+    lfs_bd_erase(&lfs, rbyd.block) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4, NULL)) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4, NULL)) => 0;
+
+    lfs_off_t off;
+    lfs_size_t size;
+    lfs_srtag_t tag = lfs_rbyd_lookup(&lfs, &rbyd, 0, &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 1, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 2, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_ERR_NOENT);
+
+    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, 0, &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 1, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_MKRTAG(GSTATE, 2, 0));
+    tag = lfs_rbyd_lookup(&lfs, &rbyd, lfs_rtag_inc(tag), &off, &size);
+    assert(tag == LFS_ERR_NOENT);
+'''
 
 [cases.test_rbyd_bifoliate]
 in = 'lfs.c'
@@ -321,7 +409,7 @@ code = '''
         .erased = true,
     };
 
-    // ignore a black edge 
+    // ignore a black edge
     //   <b           <b
     // .-'|  =>  .----'|
     // 1  2      1  2  2
@@ -374,7 +462,7 @@ code = '''
         .erased = true,
     };
 
-    // ignore a black edge 
+    // ignore a black edge
     //                <r
     //           .----'|
     //   <b  =>  |    <b
@@ -471,7 +559,7 @@ code = '''
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
             LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4, 
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
             LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
 
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
@@ -493,7 +581,7 @@ code = '''
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
             LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4, 
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
 
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
@@ -515,7 +603,7 @@ code = '''
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xaaaaaaaa}, 4,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xcccccccc}, 4, 
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xcccccccc}, 4,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
 
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
@@ -584,7 +672,7 @@ code = '''
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
             LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4, 
+            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
             LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
 
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
@@ -610,7 +698,7 @@ code = '''
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xaaaaaaaa}, 4,
             LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4, 
+            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
 
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
@@ -636,7 +724,7 @@ code = '''
     lfs_rbyd_commit(&lfs, &rbyd,
             LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xaaaaaaaa}, 4,
             LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
-            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4, 
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
             LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
 
     lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
@@ -649,3 +737,653 @@ code = '''
     lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
             => LFS_MKRTAG(GSTATE, 4, 0);
 '''
+
+[cases.test_rbyd_rotations]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_init(&lfs, cfg) => 0;
+
+    lfs_rbyd_t rbyd_init = {
+        .block = 0,
+        .trunk = 0,
+        .noff = 0,
+        .rev = 1,
+        .crc = 0,
+        .count = 0,
+        .erased = true,
+    };
+
+    // all three the same
+    //                      <y
+    //              .-------'|
+    //      <r      |       <r
+    // .----'|  =>  |  .----'|
+    // |    <b      |  |    <b
+    // |  .-'|      |  |  .-'|
+    // 1  2  3      1  2  3  4
+    lfs_rbyd_t rbyd = rbyd_init;
+    lfs_bd_erase(&lfs, rbyd.block) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
+
+    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+    lfs_off_t off;
+    lfs_size_t size;
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 1, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 2, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 3, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 4, 0);
+
+    // yellow and red alt the same
+    //                      <y
+    //              .-------'|
+    //      <r      |       <r
+    // .----'|  =>  |  .----'|
+    // |    <b      |  |    >b
+    // |  .-'|      |  |  .-'|
+    // 1  2  4      1  2  4  3
+    rbyd = rbyd_init;
+    lfs_bd_erase(&lfs, rbyd.block) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
+
+    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 1, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 2, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 3, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 4, 0);
+
+    // yellow and black alt the same
+    //                      <y              <y
+    //              .-------'|      .-------'|
+    //      <r      |       >r      |       <r
+    // .----'|  =>  |  .----'|  =>  |     .-'|
+    // |    >b      |  |    <b      |     | >b
+    // |  .-'|      |  |  .-'|      |  .--|-'|
+    // 1  4  2      1  4  2  3      1  4  2  3
+    rbyd = rbyd_init;
+    lfs_bd_erase(&lfs, rbyd.block) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xbbbbbbbb}, 4,
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xcccccccc}, 4,
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
+
+    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 1, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 2, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 3, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 4, 0);
+
+    // red and black alt the same
+    //                      >y              <y
+    //              .-------'|         .----'|
+    //      >r      |       <r         |    <r
+    // .----'|  =>  |  .----'|  =>     |  .-'|
+    // |    <b      |  |    <b         |  | >b
+    // |  .-'|      |  |  .-'|      .--|--|-'|
+    // 4  1  2      4  1  2  3      4  1  2  3
+    rbyd = rbyd_init;
+    lfs_bd_erase(&lfs, rbyd.block) => 0;
+    lfs_rbyd_commit(&lfs, &rbyd,
+            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xbbbbbbbb}, 4,
+            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xcccccccc}, 4,
+            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xdddddddd}, 4, NULL))))) => 0;
+
+    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 1, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 2, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 3, 0);
+    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+            => LFS_MKRTAG(GSTATE, 4, 0);
+'''
+
+#[cases.test_rbyd_ysplits]
+#in = 'lfs.c'
+#code = '''
+#    lfs_t lfs;
+#    lfs_init(&lfs, cfg) => 0;
+#
+#    lfs_rbyd_t rbyd_init = {
+#        .block = 0,
+#        .trunk = 0,
+#        .noff = 0,
+#        .rev = 1,
+#        .crc = 0,
+#        .count = 0,
+#        .erased = true,
+#    };
+#
+#    // split a yellow triple, not taking any alt
+#    //                            <b
+#    //                          .-'|
+#    //         <y              <y  |
+#    // .-------'|      .-------'|  |
+#    // |       <r  =>  |       <r  |
+#    // |  .----'|      |  .----'   |
+#    // |  |    <b      |  |       <b
+#    // |  |  .-'|      |  |  .----'|
+#    // 1  2  3  4      1  2  3  4  4
+#    lfs_rbyd_t rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_off_t off;
+#    lfs_size_t size;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#
+#    // split a yellow triple, taking the black alt
+#    //                            <b
+#    //                          .-'|
+#    //         <y              <y  |
+#    // .-------'|      .-------'|  |
+#    // |       <r  =>  |       <r  |
+#    // |  .----'|      |  .----'   |
+#    // |  |    <b      |  |       >b
+#    // |  |  .-'|      |  |     .-'|
+#    // 1  2  3  4      1  2  3  4  3
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#
+#    // split a yellow triple, taking the red alt
+#    //         <y                 >b
+#    // .-------'|               .-'|
+#    // |       <r               | <b
+#    // |  .----'|  =>  .--------|-'|
+#    // |  |    <b      |       <b  |
+#    // |  |  .-'|      |     .-'|  |
+#    // 1  2  3  4      1  2  3  4  2
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#
+#    // split a yellow triple, taking the yellow alt
+#    //         <y                 >b
+#    // .-------'|               .-'|
+#    // |       <r               | >b
+#    // |  .----'|  =>     .-----|-'|
+#    // |  |    <b         |    <b  |
+#    // |  |  .-'|         |  .-'|  |
+#    // 1  2  3  4      1  2  3  4  1
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#'''
+#
+#[cases.test_rbyd_quintifoliate]
+#in = 'lfs.c'
+#code = '''
+#    lfs_t lfs;
+#    lfs_init(&lfs, cfg) => 0;
+#
+#    lfs_rbyd_t rbyd_init = {
+#        .block = 0,
+#        .trunk = 0,
+#        .noff = 0,
+#        .rev = 1,
+#        .crc = 0,
+#        .count = 0,
+#        .erased = true,
+#    };
+#
+#    // split a yellow triple, not taking any alt
+#    //                            <b
+#    //                          .-'|
+#    //                         <y  |
+#    //                 .-------'|  |
+#    //         <y      |       <r  |
+#    // .-------'|  =>  |  .----'   |
+#    // |       <r      |  |       <r
+#    // |  .----'|      |  |  .----'|
+#    // |  |    <b      |  |  |    <b
+#    // |  |  .-'|      |  |  |  .-'|
+#    // 1  2  3  4      1  2  3  4  5
+#    lfs_rbyd_t rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_off_t off;
+#    lfs_size_t size;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#
+#    // split a yellow triple, taking the black alt
+#    //                            <b
+#    //                          .-'|
+#    //                         <y  |
+#    //                 .-------'|  |
+#    //         <y      |       <r  |
+#    // .-------'|  =>  |  .----'   |
+#    // |       <r      |  |       >r
+#    // |  .----'|      |  |     .-'|
+#    // |  |    <b      |  |     | >b
+#    // |  |  .-'|      |  |  .--|-'|
+#    // 1  2  4  5      1  2  4  5  3
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#
+#    // split a yellow triple, taking the red alt
+#    //                            >b
+#    //                          .-'|
+#    //         <y               | <r
+#    // .-------'|      .--------|-'|
+#    // |       <r      |        | >b
+#    // |  .----'|  =>  |  .-----|-'|
+#    // |  |    <b      |  |    <b  |
+#    // |  |  .-'|      |  |  .-'|  |
+#    // 1  3  4  5      1  3  4  5  2
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#
+#    // split a yellow triple, taking the yellow alt
+#    //                            >b
+#    //                          .-'|
+#    //         <y               | >r
+#    // .-------'|         .-----|-'|
+#    // |       <r         |     | >b
+#    // |  .----'|  =>  .--|-----|-'|
+#    // |  |    <b      |  |    <b  |
+#    // |  |  .-'|      |  |  .-'|  |
+#    // 2  3  4  5      2  3  4  5  1
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xeeeeeeee}, 4, NULL)))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#'''
+#[cases.test_rbyd_prunes]
+#in = 'lfs.c'
+#code = '''
+#    lfs_t lfs;
+#    lfs_init(&lfs, cfg) => 0;
+#
+#    lfs_rbyd_t rbyd_init = {
+#        .block = 0,
+#        .trunk = 0,
+#        .noff = 0,
+#        .rev = 1,
+#        .crc = 0,
+#        .count = 0,
+#        .erased = true,
+#    };
+#
+#    // don't prune
+#    //            <b                    <b
+#    //          .-'|               .----'|
+#    //         <y  |              <y     |
+#    // .-------'|  |      .-------'|     |
+#    // |       <r  |      |       <r     |
+#    // |  .----'   |  =>  |  .----'      |
+#    // |  |       <r      |  |          <r
+#    // |  |  .----'|      |  |  .-------'|
+#    // |  |  |    <b      |  |  |       <b
+#    // |  |  |  .-'|      |  |  |  .----'|
+#    // 1  2  3  4  5      1  2  3  4  5  5
+#    lfs_rbyd_t rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xeeeeeeee}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xffffffff}, 4, NULL))))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_off_t off;
+#    lfs_size_t size;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#
+#    // prune by taking a red alt
+#    //            <b
+#    //          .-'|
+#    //         <y  |                    >b
+#    // .-------'|  |                  .-'|
+#    // |       <r  |                  | <b
+#    // |  .----'   |  =>  .-----------|-'|
+#    // |  |       <r      |          <r  |
+#    // |  |  .----'|      |     .----'|  |
+#    // |  |  |    <b      |     |    <b  |
+#    // |  |  |  .-'|      |     |  .-'|  |
+#    // 1  2  3  4  5      1  2  3  4  5  2
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xeeeeeeee}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xeeeeeeee}, 4, NULL))))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#
+#    // prune by taking a yellow alt (this needs to prune during the rflip)
+#    //            <b
+#    //          .-'|
+#    //         <y  |                    >b
+#    // .-------'|  |                  .-'|
+#    // |       <r  |                  | >b
+#    // |  .----'   |  =>     .--------|-'|
+#    // |  |       <r         |       <r  |
+#    // |  |  .----'|         |  .----'|  |
+#    // |  |  |    <b         |  |    <b  |
+#    // |  |  |  .-'|         |  |  .-'|  |
+#    // 1  2  3  4  5      1  2  3  4  5  1
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xeeeeeeee}, 4,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xeeeeeeee}, 4, NULL))))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#'''
+#
+#[cases.test_rbyd_sextifoliate]
+#in = 'lfs.c'
+#code = '''
+#    lfs_t lfs;
+#    lfs_init(&lfs, cfg) => 0;
+#
+#    lfs_rbyd_t rbyd_init = {
+#        .block = 0,
+#        .trunk = 0,
+#        .noff = 0,
+#        .rev = 1,
+#        .crc = 0,
+#        .count = 0,
+#        .erased = true,
+#    };
+#
+#    // don't prune
+#    //                                  <b
+#    //                             .----'|
+#    //            <b              <y     |
+#    //          .-'|      .-------'|     |
+#    //         <y  |      |       <r     |
+#    // .-------'|  |      |  .----'      |
+#    // |       <r  |      |  |          <y
+#    // |  .----'   |  =>  |  |  .-------'|
+#    // |  |       <r      |  |  |       <r
+#    // |  |  .----'|      |  |  |  .----'|
+#    // |  |  |    <b      |  |  |  |    <b
+#    // |  |  |  .-'|      |  |  |  |  .-'|
+#    // 1  2  3  4  5      1  2  3  4  5  6
+#    lfs_rbyd_t rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xeeeeeeee}, 4,
+#            LFS_MKRATTR(GSTATE, 6, 0, &(uint32_t){0xffffffff}, 4, NULL))))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_off_t off;
+#    lfs_size_t size;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 6, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 6, 0);
+#
+#    // prune by taking a red alt
+#    //            <b                    >b
+#    //          .-'|                  .-'|
+#    //         <y  |                  | <r
+#    // .-------'|  |      .-----------|-'|
+#    // |       <r  |      |           | >b
+#    // |  .----'   |  =>  |  .--------|-'|
+#    // |  |       <r      |  |       <r  |
+#    // |  |  .----'|      |  |  .----'|  |
+#    // |  |  |    <b      |  |  |    <b  |
+#    // |  |  |  .-'|      |  |  |  .-'|  |
+#    // 1  3  4  5  6      1  3  4  5  6  2
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 6, 0, &(uint32_t){0xeeeeeeee}, 4,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xeeeeeeee}, 4, NULL))))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 6, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 6, 0);
+#
+#    // prune by taking a yellow alt (this needs to prune during the rflip)
+#    //            <b                    >b
+#    //          .-'|                  .-'|
+#    //         <y  |                  | >r
+#    // .-------'|  |         .--------|-'|
+#    // |       <r  |         |        | >b
+#    // |  .----'   |  =>  .--|--------|-'|
+#    // |  |       <r      |  |       <r  |
+#    // |  |  .----'|      |  |  .----'|  |
+#    // |  |  |    <b      |  |  |    <b  |
+#    // |  |  |  .-'|      |  |  |  .-'|  |
+#    // 2  3  4  5  6      2  3  4  5  6  1
+#    rbyd = rbyd_init;
+#    lfs_bd_erase(&lfs, rbyd.block) => 0;
+#    lfs_rbyd_commit(&lfs, &rbyd,
+#            LFS_MKRATTR(GSTATE, 2, 0, &(uint32_t){0xaaaaaaaa}, 4,
+#            LFS_MKRATTR(GSTATE, 3, 0, &(uint32_t){0xbbbbbbbb}, 4,
+#            LFS_MKRATTR(GSTATE, 4, 0, &(uint32_t){0xcccccccc}, 4,
+#            LFS_MKRATTR(GSTATE, 5, 0, &(uint32_t){0xdddddddd}, 4,
+#            LFS_MKRATTR(GSTATE, 6, 0, &(uint32_t){0xeeeeeeee}, 4,
+#            LFS_MKRATTR(GSTATE, 1, 0, &(uint32_t){0xeeeeeeee}, 4, NULL))))))) => 0;
+#
+#    lfs_rbyd_fetch(&lfs, &rbyd, rbyd.block, NULL) => 0;
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 1, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 1, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 2, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 2, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 3, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 3, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 4, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 4, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 5, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 5, 0);
+#    lfs_rbyd_lookup(&lfs, &rbyd, LFS_MKRTAG(GSTATE, 6, 0), &off, &size)
+#            => LFS_MKRTAG(GSTATE, 6, 0);
+#'''