:meth:`.WNetworkNativeTransportProto.server_socket` method implementation

def server_socket(self, config):
		""" :meth:`.WNetworkNativeTransportProto.server_socket` method implementation
		"""
		if self.__server_socket is None:
			self.__server_socket = self.create_server_socket(config)
			self.__server_socket.bind(self.bind_socket(config).pair())
		return self.__server_socket