def CallMethod(self, method_descriptor, rpc_controller,
                 request, response_class, done):
    """Calls the method identified by the descriptor.

    Call the given method of the remote service.  The signature of this
    procedure looks the same as Service.CallMethod(), but the requirements
    are less strict in one important way:  the request object doesn't have to
    be of any specific class as long as its descriptor is method.input_type.
    """
    raise NotImplementedError
Calls the method identified by the descriptor.

    Call the given method of the remote service.  The signature of this
    procedure looks the same as Service.CallMethod(), but the requirements
    are less strict in one important way:  the request object doesn't have to
    be of any specific class as long as its descriptor is method.input_type.
    
deps/protobuf/python/google/protobuf/service.py