def get_teams():
        """
        :return: all knows teams
        """
        LOGGER.debug("TeamService.get_teams")
        args = {'http_operation': 'GET', 'operation_path': ''}
        response = TeamService.requester.call(args)
        ret = None
        if response.rc == 0:
            ret = []
            for team in response.response_content['teams']:
                ret.append(Team.json_2_team(team))
        elif response.rc != 404:
            err_msg = 'TeamService.get_teams - Problem while getting teams. ' \
                      '. Reason: ' + str(response.response_content) + '-' + str(response.error_message) + \
                      " (" + str(response.rc) + ")"
            LOGGER.warning(err_msg)
        return ret
:return: all knows teams