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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def join(self, group_id, share_token):
 """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` """

        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)