def _initialize_builtins():
  for filename in os.listdir(_handler_dir):
    if os.path.isfile(_get_yaml_path(filename, '')):
      _available_builtins.append(filename)
Scan the immediate subdirectories of the builtins module.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/builtins/__init__.py/_initialize_builtins