'Update the public key to ip mapping
:param trader_id: The public key of the node
:param ip: The ip and port of the node
:type trader_id: TraderId
:type ip: tuple'

def update_ip(self, trader_id, ip):

    assert isinstance(trader_id, TraderId), type(trader_id)
    assert isinstance(ip, tuple), type(ip)
    assert isinstance(ip[0], str)
    assert isinstance(ip[1], int)
    self._logger.debug('Updating    ip    of    trader    %s    to    (%s,    %s)', trader_id, ip[0], ip[1])
    self.mid_register[trader_id] = ip
