(func)
return wrapper
A delegated method raises AttributeError in the absence of backend
    support.
A delegated method raises AttributeError in the absence of backend
    support.
A delegated method raises AttributeError in the absence of backend support .
def delegated(func):
    """A delegated method raises AttributeError in the absence of backend
    support."""
    @wraps(func)
    def wrapper(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except KeyError:
            raise ImplementationError(
                "Method '%s' not provided by registered "
                "implementation '%s'" % (func.__name__, args[0].impl))
    return wrapper
def delegated ( func ) : @ wraps ( func ) def wrapper ( * args , * * kwargs ) : try : return func ( * args , * * kwargs ) except KeyError : raise ImplementationError ( "Method '%s' not provided by registered " "implementation '%s'" % ( func . __name__ , args [ 0 ] . impl ) ) return wrapper