:return: all knows environments

def get_environments():
        """
        :return: all knows environments
        """
        LOGGER.debug("EnvironmentService.get_environments")
        args = {'http_operation': 'GET', 'operation_path': ''}
        response = EnvironmentService.requester.call(args)
        ret = None
        if response.rc == 0:
            ret = []
            for environment in response.response_content['environments']:
                ret.append(Environment.json_2_environment(environment))
        elif response.rc != 404:
            err_msg = 'EnvironmentService.get_environments - Problem while getting environments. ' \
                      'Reason: ' + str(response.response_content) + '-' + str(response.error_message) + \
                      " (" + str(response.rc) + ")"
            LOGGER.warning(err_msg)
        return ret