'Make the next=... URL parameter that indicates where the user should go next.
>>> _finish_auth_url_param([(\'next\', \'/dashboard\')])
\'/account/finish_auth?next=%2Fdashboard\''

def _finish_auth_url_param(self, params):

    return urlencode({'next': '/account/finish_auth?{}'.format(urlencode(params))})
