In asynchronous mode, returns immediately, returning *self*. The :attr:`event` attribute will be set when the reply has been received (see :attr:`reply`) or an error occured (see :attr:`error`).
- :param op: operation to b\e requested
- :type ops: `~xml.etree.ElementTree.Element`
+ *op* operation to be requested as an `~xml.etree.ElementTree.Element`
- :rtype: `RPCReply` (sync) or `RPC` (async)
+ Returns :class:`RPCReply` (sync) or :class:`RPC` (async)
"""
logger.info('Requesting %r' % self.__class__.__name__)
req = self._wrap(op)