--- /dev/null
+"use strict";
+
+module.exports.mixin = function mixin(target, source) {
+ const keys = Object.getOwnPropertyNames(source);
+ for (let i = 0; i < keys.length; ++i) {
+ Object.defineProperty(target, keys[i], Object.getOwnPropertyDescriptor(source, keys[i]));
+ }
+};
+
+module.exports.wrapperSymbol = Symbol("wrapper");
+module.exports.implSymbol = Symbol("impl");
+
+module.exports.wrapperForImpl = function (impl) {
+ return impl[module.exports.wrapperSymbol];
+};
+
+module.exports.implForWrapper = function (wrapper) {
+ return wrapper[module.exports.implSymbol];
+};
+