Express addition

node_modules/core-js/modules/_an-instance.js

@@ -0,0 +1,5 @@
+module.exports = function (it, Constructor, name, forbiddenField) {
+  if (!(it instanceof Constructor) || (forbiddenField !== undefined && forbiddenField in it)) {
+    throw TypeError(name + ': incorrect invocation!');
+  } return it;
+};