text: "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];
  };
  
  