'Get the version of the server.
@return: a deferred that will fire with the string value of the
version.
@rtype: L{Deferred}'

def version(self):

    if self._disconnected:
        return fail(RuntimeError('not    connected'))
    self.sendLine('version')
    cmdObj = Command('version')
    self._current.append(cmdObj)
    return cmdObj._deferred
