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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 get_group(self, group_id):
 """Get a single group. :param str group_id: group ID :returns: group :rtype: :class:`marathon.models.group.MarathonGroup` """

        response = self._do_request(
            'GET', '/v2/groups/{group_id}'.format(group_id=group_id))
        return self._parse_response(response, MarathonGroup)