def initiate(self, callback=None):
        """
        Initiate an OAuth handshake with MediaWiki.

        :Parameters:
            callback : `str`
                Callback URL. Defaults to 'oob'.

        :Returns:
            A `tuple` of two values:

            * a MediaWiki URL to direct the user to
            * a :class:`~mwoauth.RequestToken` representing an access request


        """
        return initiate(self.mw_uri, self.consumer_token,
                        callback=callback or self.callback,
                        user_agent=self.user_agent)