code: def join(self, group_id, share_token):
          
          path = '{}/join/{}'.format(group_id, share_token)
          url = utils.urljoin(self.url, path)
          response = self.session.post(url)
          group = response.data['group']
          return Group(self, **group)
docs: Join a group using a share token.
  
          :param str group_id: the group_id of a group
          :param str share_token: the share token
          :return: the group
          :rtype: :class:`~groupy.api.groups.Group`