text: -- make sure the prerequisite libraries are loaded
  DO '1' LANGUAGE plpythonu;
  SELECT NULL::ltree;
  
  
  CREATE FUNCTION ltree_to_plpython(val internal) RETURNS internal
  LANGUAGE C STRICT IMMUTABLE
  AS 'MODULE_PATHNAME';
  
  CREATE TRANSFORM FOR ltree LANGUAGE plpythonu (
      FROM SQL WITH FUNCTION ltree_to_plpython(internal)
  );
  