'Return an object which represents the *claimed* (not verified) user
id of the credentials present in the request. ``None`` if there is no
:term:`authentication policy` in effect or there is no user data
associated with the current request.  This differs from
:attr:`~pyramid.request.Request.authenticated_userid`, because the
effective authentication policy will not ensure that a record
associated with the userid exists in persistent storage.
.. versionadded:: 1.5'

@property
def unauthenticated_userid(self):

    policy = self._get_authentication_policy()
    if (policy is None):
        return None
    return policy.unauthenticated_userid(self)
