+external text_startswith : tree -> string -> [`Text ] node array = "caml_text_collection_startswith"
+external text_endswith : tree -> string -> [`Text ] node array = "caml_text_collection_endswith"
+external text_equals : tree -> string -> [`Text ] node array = "caml_text_collection_equals"
+external text_unsorted_contains : tree -> string -> [`Text ] node array = "caml_text_collection_unsorted_contains"