@classmethod
def get_url(cls, participant_code, name_in_url, page_index):
    """need this because reverse() is too slow in create_session"""
    return '/p/{pcode}/{name_in_url}/{ClassName}/{page_index}/'.format(pcode
        =participant_code, name_in_url=name_in_url, ClassName=cls.__name__,
        page_index=page_index)
