Express addition

node_modules/core-js/modules/_to-index.js

@@ -0,0 +1,10 @@
+// https://tc39.github.io/ecma262/#sec-toindex
+var toInteger = require('./_to-integer');
+var toLength = require('./_to-length');
+module.exports = function (it) {
+  if (it === undefined) return 0;
+  var number = toInteger(it);
+  var length = toLength(number);
+  if (number !== length) throw RangeError('Wrong length!');
+  return length;
+};