'Asynchronously send credentials to server. Takes the same
arguments as :meth:`add_auth`.
:rtype: :class:`~kazoo.interfaces.IAsyncResult`'

def add_auth_async(self, scheme, credential):

    if (not isinstance(scheme, basestring)):
        raise TypeError('Invalid    type    for    scheme')
    if (not isinstance(credential, basestring)):
        raise TypeError('Invalid    type    for    credential')
    self.auth_data.add((scheme, credential))
    async_result = self.handler.async_result()
    self._call(Auth(0, scheme, credential), async_result)
    return async_result
