Express addition

node_modules/core-js/modules/_advance-string-index.js

@@ -0,0 +1,8 @@
+'use strict';
+var at = require('./_string-at')(true);
+
+ // `AdvanceStringIndex` abstract operation
+// https://tc39.github.io/ecma262/#sec-advancestringindex
+module.exports = function (S, index, unicode) {
+  return index + (unicode ? at(S, index).length : 1);
+};