(function (child, parent) {
  if (typeof parent !== "function" && parent !== null) {
    throw new TypeError("Super expression must either be null or a function, not " + typeof parent);
  }
  child.prototype = Object.create(parent && parent.prototype, {
    constructor: {
      value: child,
      enumerable: false,
      writable: true,
      configurable: true
    }
  });
  if (parent) child.__proto__ = parent;
})