Index: node_modules/agentkeepalive/lib/constants.js
===================================================================
--- node_modules/agentkeepalive/lib/constants.js	(revision 81bc7da776d8cda42939ef4ab350c88d13b4941f)
+++ node_modules/agentkeepalive/lib/constants.js	(revision 81bc7da776d8cda42939ef4ab350c88d13b4941f)
@@ -0,0 +1,14 @@
+'use strict';
+
+module.exports = {
+  // agent
+  CURRENT_ID: Symbol('agentkeepalive#currentId'),
+  CREATE_ID: Symbol('agentkeepalive#createId'),
+  INIT_SOCKET: Symbol('agentkeepalive#initSocket'),
+  CREATE_HTTPS_CONNECTION: Symbol('agentkeepalive#createHttpsConnection'),
+  // socket
+  SOCKET_CREATED_TIME: Symbol('agentkeepalive#socketCreatedTime'),
+  SOCKET_NAME: Symbol('agentkeepalive#socketName'),
+  SOCKET_REQUEST_COUNT: Symbol('agentkeepalive#socketRequestCount'),
+  SOCKET_REQUEST_FINISHED_COUNT: Symbol('agentkeepalive#socketRequestFinishedCount'),
+};