'When :attr:`~.Cluster.protocol_version` is 2 or higher, this should
be an instance of a subclass of :class:`~cassandra.auth.AuthProvider`,
such as :class:`~.PlainTextAuthProvider`.
When :attr:`~.Cluster.protocol_version` is 1, this should be
a function that accepts one argument, the IP address of a node,
and returns a dict of credentials for that node.
When not using authentication, this should be left as :const:`None`.'

@property
def auth_provider(self):

    return self._auth_provider
