code: def _extern_decl(return_type, arg_types):
    
    def wrapper(func):
      signature = _ExternSignature(
        return_type=str(return_type),
        method_name=str(func.__name__),
        arg_types=tuple(arg_types))
      func.extern_signature = signature
      return func
    return wrapper
docs: A decorator for methods corresponding to extern functions. All types should be strings.
  
    The _FFISpecification class is able to automatically convert these into method declarations for
    cffi.