@abstractmethod<EOL><INDENT>def fulfill(self, user, request=None):<DEDENT>
return NotImplemented<EOL>
Abstract method called to verify the requirement against the current
user and request.

.. versionchanged:: 0.5.0
    Passing request is now deprecated, pending removal in version 1.0.0

:param user: The current identity
:param request: The current request.