async def get_connection(self, hostname=None):
        """
        **coroutine** Get connection from next available host in a round robin
        fashion.

        :returns: :py:class:`Connection<aiogremlin.driver.connection.Connection>`
        """
        if not self._hosts:
            await self.establish_hosts()
        if hostname:
            try:
                host = self._hostmap[hostname]
            except KeyError:
                raise exception.ConfigError(
                    'Unknown host: {}'.format(hostname))
        else:
            host = self._hosts.popleft()
        conn = await host.get_connection()
        self._hosts.append(host) 
        return conn