<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def send(self, event):
 """Convert a high-level event into bytes that can be sent to the peer, while updating our internal state machine. Args: event: The :ref:`event <events>` to send. Returns: If ``type(event) is ConnectionClosed``, then returns ``None``. Otherwise, returns a :term:`bytes-like object`. Raises: LocalProtocolError: Sending this event at this time would violate our understanding of the HTTP/1.1 protocol. If this method raises any exception then it also sets :attr:`Connection.our_state` to :data:`ERROR` -- see :ref:`error-handling` for discussion. """

        data_list = self.send_with_data_passthrough(event)
        if data_list is None:
            return None
        else:
            return b"".join(data_list)