typedef struct Tree<> {
  /* future Code */
  /* Type* tree; */
  /* Type* node; */
  union Data* tree;
  struct Node* node;
  __code put(Impl* tree, Type* node, __code next(...));
  __code get(Impl* tree, Type* node, __code next(...));
  __code remove(Impl* tree, Type* node, __code next(...));
  // __code clearRedBlackTree();
  __code next(...);
} Tree;