'List API versions
For a full list of available parameters, please refer to the official
API reference:
https://developer.openstack.org/api-ref/block-storage/v3/#list-all-api-versions'

def list_versions(self):

    version_url = self._get_base_version_url()
    start = time.time()
    (resp, body) = self.raw_request(version_url, 'GET')
    end = time.time()
    self._log_request('GET', version_url, resp, secs=(end - start), resp_body=body)
    self._error_checker(resp, body)
    body = json.loads(body)
    self.validate_response(schema.list_versions, resp, body)
    return rest_client.ResponseBody(resp, body)
