diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index 3873ba5..ca6de00 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -464,13 +464,107 @@ template <class Stepwise> void runSequential(std::span<Stepwise> remaining) {
   }
 }
 
+struct ReferenceImpl {
+  explicit ReferenceImpl(int64_t oldestVersion) : oldestVersion(oldestVersion) {
+    writeVersionMap[""] = oldestVersion;
+  }
+  void check(const ConflictSet::ReadRange *reads, ConflictSet::Result *results,
+             int count) const {
+    for (int i = 0; i < count; ++i) {
+      if (reads[i].readVersion < oldestVersion) {
+        results[i] = ConflictSet::TooOld;
+        continue;
+      }
+      auto begin =
+          std::string((const char *)reads[i].begin.p, reads[i].begin.len);
+      auto end =
+          reads[i].end.len == 0
+              ? begin + std::string("\x00", 1)
+              : std::string((const char *)reads[i].end.p, reads[i].end.len);
+      int64_t maxVersion = oldestVersion;
+      for (auto iter = --writeVersionMap.upper_bound(begin),
+                endIter = writeVersionMap.lower_bound(end);
+           iter != endIter; ++iter) {
+        maxVersion = std::max(maxVersion, iter->second);
+      }
+      results[i] = maxVersion > reads[i].readVersion ? ConflictSet::Conflict
+                                                     : ConflictSet::Commit;
+    }
+  }
+  void addWrites(const ConflictSet::WriteRange *writes, int count) {
+    for (int i = 0; i < count; ++i) {
+      auto begin =
+          std::string((const char *)writes[i].begin.p, writes[i].begin.len);
+      auto end =
+          writes[i].end.len == 0
+              ? begin + std::string("\x00", 1)
+              : std::string((const char *)writes[i].end.p, writes[i].end.len);
+      auto writeVersion = writes[i].writeVersion;
+      auto prevVersion = (--writeVersionMap.upper_bound(end))->second;
+      for (auto iter = writeVersionMap.lower_bound(begin),
+                endIter = writeVersionMap.lower_bound(end);
+           iter != endIter;) {
+        iter = writeVersionMap.erase(iter);
+      }
+      writeVersionMap[begin] = writeVersion;
+      writeVersionMap[end] = prevVersion;
+    }
+  }
+
+  void setOldestVersion(int64_t oldestVersion) {
+    this->oldestVersion = oldestVersion;
+  }
+
+  void printLogical(std::string &result) {
+    for (const auto &[k, v] : writeVersionMap) {
+      std::string key;
+      for (uint8_t c : k) {
+        key += "x";
+        key += "0123456789abcdef"[c / 16];
+        key += "0123456789abcdef"[c % 16];
+      }
+      result += key + " -> " + std::to_string(v) + "\n";
+    }
+  }
+
+  int64_t oldestVersion;
+  std::map<std::string, int64_t> writeVersionMap;
+};
+
+using Key = ConflictSet::Key;
+
+[[maybe_unused]] Key toKey(Arena &arena, int n) {
+  constexpr int kMaxLength = 8;
+  int i = kMaxLength;
+  uint8_t *itoaBuf = new (arena) uint8_t[kMaxLength];
+  memset(itoaBuf, '0', kMaxLength);
+  do {
+    itoaBuf[--i] = "0123456789abcdef"[n % 16];
+    n /= 16;
+  } while (n);
+  return Key{itoaBuf, kMaxLength};
+}
+
+[[maybe_unused]] Key toKeyAfter(Arena &arena, int n) {
+  constexpr int kMaxLength = 8;
+  int i = kMaxLength;
+  uint8_t *itoaBuf = new (arena) uint8_t[kMaxLength + 1];
+  memset(itoaBuf, '0', kMaxLength);
+  itoaBuf[kMaxLength] = 0;
+  do {
+    itoaBuf[--i] = "0123456789abcdef"[n % 16];
+    n /= 16;
+  } while (n);
+  return Key{itoaBuf, kMaxLength + 1};
+}
+
 // ==================== END UTILITIES IMPL ====================
 
+// ==================== BEGIN IMPLEMENTATION ====================
+
 #define SHOW_PRIORITY 0
 #define DEBUG 0
 
-using Key = ConflictSet::Key;
-
 static auto operator<=>(const Key &lhs, const Key &rhs) {
   const int minLen = std::min(lhs.len, rhs.len);
   const int c = memcmp(lhs.p, rhs.p, minLen);
@@ -738,34 +832,7 @@ void lastLeqMulti(Arena &arena, Node *root, std::span<Key> keys,
   }
 }
 
-[[maybe_unused]] Key toKey(Arena &arena, int n) {
-  constexpr int kMaxLength = 8;
-  int i = kMaxLength;
-  uint8_t *itoaBuf = new (arena) uint8_t[kMaxLength];
-  memset(itoaBuf, '0', kMaxLength);
-  do {
-    itoaBuf[--i] = "0123456789abcdef"[n % 16];
-    n /= 16;
-  } while (n);
-  return Key{itoaBuf, kMaxLength};
-}
-
-[[maybe_unused]] Key toKeyAfter(Arena &arena, int n) {
-  constexpr int kMaxLength = 8;
-  int i = kMaxLength;
-  uint8_t *itoaBuf = new (arena) uint8_t[kMaxLength + 1];
-  memset(itoaBuf, '0', kMaxLength);
-  itoaBuf[kMaxLength] = 0;
-  do {
-    itoaBuf[--i] = "0123456789abcdef"[n % 16];
-    n /= 16;
-  } while (n);
-  return Key{itoaBuf, kMaxLength + 1};
-}
-
 // Recompute maxVersion, and propagate up the tree as necessary
-// TODO interleave this? Will require careful analysis for correctness, and the
-// performance gains may not be worth it.
 void updateMaxVersion(Node *n) {
   for (;;) {
     int64_t maxVersion = std::max(n->pointVersion, n->rangeVersion);
@@ -847,7 +914,6 @@ void rotate(Node **node, bool dir) {
   return expected;
 }
 
-template <class ReferenceImpl>
 bool checkCorrectness(Node *node, ReferenceImpl &refImpl) {
   bool success = true;
   // Check bst invariant
@@ -1073,6 +1139,8 @@ struct __attribute__((__visibility__("hidden"))) ConflictSet::Impl {
   }
 };
 
+// ==================== END IMPLEMENTATION ====================
+
 void ConflictSet::check(const ReadRange *reads, Result *results,
                         int count) const {
   return impl->check(reads, results, count);
@@ -1140,73 +1208,6 @@ namespace std {
 void __throw_length_error(const char *) { __builtin_unreachable(); }
 } // namespace std
 
-struct ReferenceImpl {
-  explicit ReferenceImpl(int64_t oldestVersion) : oldestVersion(oldestVersion) {
-    writeVersionMap[""] = oldestVersion;
-  }
-  void check(const ConflictSet::ReadRange *reads, ConflictSet::Result *results,
-             int count) const {
-    for (int i = 0; i < count; ++i) {
-      if (reads[i].readVersion < oldestVersion) {
-        results[i] = ConflictSet::TooOld;
-        continue;
-      }
-      auto begin =
-          std::string((const char *)reads[i].begin.p, reads[i].begin.len);
-      auto end =
-          reads[i].end.len == 0
-              ? begin + std::string("\x00", 1)
-              : std::string((const char *)reads[i].end.p, reads[i].end.len);
-      int64_t maxVersion = oldestVersion;
-      for (auto iter = --writeVersionMap.upper_bound(begin),
-                endIter = writeVersionMap.lower_bound(end);
-           iter != endIter; ++iter) {
-        maxVersion = std::max(maxVersion, iter->second);
-      }
-      results[i] = maxVersion > reads[i].readVersion ? ConflictSet::Conflict
-                                                     : ConflictSet::Commit;
-    }
-  }
-  void addWrites(const ConflictSet::WriteRange *writes, int count) {
-    for (int i = 0; i < count; ++i) {
-      auto begin =
-          std::string((const char *)writes[i].begin.p, writes[i].begin.len);
-      auto end =
-          writes[i].end.len == 0
-              ? begin + std::string("\x00", 1)
-              : std::string((const char *)writes[i].end.p, writes[i].end.len);
-      auto writeVersion = writes[i].writeVersion;
-      auto prevVersion = (--writeVersionMap.upper_bound(end))->second;
-      for (auto iter = writeVersionMap.lower_bound(begin),
-                endIter = writeVersionMap.lower_bound(end);
-           iter != endIter;) {
-        iter = writeVersionMap.erase(iter);
-      }
-      writeVersionMap[begin] = writeVersion;
-      writeVersionMap[end] = prevVersion;
-    }
-  }
-
-  void setOldestVersion(int64_t oldestVersion) {
-    this->oldestVersion = oldestVersion;
-  }
-
-  void printLogical(std::string &result) {
-    for (const auto &[k, v] : writeVersionMap) {
-      std::string key;
-      for (uint8_t c : k) {
-        key += "x";
-        key += "0123456789abcdef"[c / 16];
-        key += "0123456789abcdef"[c % 16];
-      }
-      result += key + " -> " + std::to_string(v) + "\n";
-    }
-  }
-
-  int64_t oldestVersion;
-  std::map<std::string, int64_t> writeVersionMap;
-};
-
 #ifdef ENABLE_TESTS
 int main(void) {
   int64_t writeVersion = 0;