def add_connection(self, conn):
        """add_connection(conn: ExtConnection) -> None
        Adds a connection to the list

        """
        if self.__connections.has_key(conn.id):
            msg = conn.name % "External Connection '%s' with repeated id"
            raise VistrailsInternalError(msg)
        self.__connections[conn.id] = conn
        self.current_id = max(self.current_id, conn.id+1)
        self.serialize()
dataset/ETHPy150Open VisTrails/VisTrails/vistrails/core/external_connection.py/ExtConnectionList.add_connection/swapped operands of `%`