Uses an executor to send an asynchronous ZMQ request to the
        validator with the handler's Connection

async def _send_request(self, request_type, payload):
        """Uses an executor to send an asynchronous ZMQ request to the
        validator with the handler's Connection
        """
        try:
            return await self._connection.send(
                message_type=request_type,
                message_content=payload,
                timeout=self._timeout)
        except DisconnectError:
            LOGGER.warning('Validator disconnected while waiting for response')
            raise errors.ValidatorDisconnected()
        except asyncio.TimeoutError:
            LOGGER.warning('Timed out while waiting for validator response')
            raise errors.ValidatorTimedOut()
        except SendBackoffTimeoutError:
            LOGGER.warning('Failed sending message - Backoff timed out')
            raise errors.SendBackoffTimeout()