a method to retrieve a list of members for a meetup group

        :param group_url: string with meetup urlname for group
        :param max_results: [optional] integer with number of members to include
        :return: dictionary with list of member details inside [json] key

        member_details = self._reconstruct_member({})

def list_group_members(self, group_url, max_results=0):

        ''' a method to retrieve a list of members for a meetup group

        :param group_url: string with meetup urlname for group
        :param max_results: [optional] integer with number of members to include
        :return: dictionary with list of member details inside [json] key

        member_details = self._reconstruct_member({})
        '''

    # https://www.meetup.com/meetup_api/docs/:urlname/members/#list

        title = '%s.list_group_members' % self.__class__.__name__

    # validate inputs
        input_fields = {
            'group_url': group_url,
            'max_results': max_results
        }
        for key, value in input_fields.items():
            if value:
                object_title = '%s(%s=%s)' % (title, key, str(value))
                self.fields.validate(value, '.%s' % key, object_title)

    # construct request fields
        url = '%s/%s/members' % (self.endpoint, group_url)
        params = {
            'fields': 'gender,birthday,last_event,messaging_pref,next_event,other_services,privacy,self,stats'
        }
        if max_results:
            params['page'] = str(max_results)

    # send request
        response_details = self._get_request(url, params=params)

    # reconstruct method output
        group_members = {
            'json': []
        }
        for key, value in response_details.items():
            if key != 'json':
                group_members[key] = value
        for member in response_details['json']:
            group_members['json'].append(self._reconstruct_member(member))

        return group_members