Try to receive some messages.
        Received messages are put on the internal queues.
        They can be retrieved using get_xxx() methods.
        Returns True if there's something queued for get_xxx() methods.

def receive_messages(self, all=False):
        """Try to receive some messages.
        Received messages are put on the internal queues.
        They can be retrieved using get_xxx() methods.
        Returns True if there's something queued for get_xxx() methods.
        """
        while all or self._incoming == 0:
            try:
                packet = self._sock.recv(4096)  # XXX the size is arbitrary
            except IOError:
                packet = None
            if not packet:
                if packet is not None:
                    # socket closed by peer
                    self._closed_by_peer = True
                break
            self._encoder.get_and_dispatch_messages(packet, self._table)
        return self._incoming > 0