// Currently...
(function () {
  var forEach = (function () {
    var forEach;
    function Properties() {
      this.toString = 1;
    }
    Properties.prototype.toString = 1;

    // Iterate over a new instance of `Properties` to detect `for...in` bugs.

    if (!size) {
      // JScript fork.
      forEach = function forEach() {
        // ...
      };
    } else if (size == 2) {
      // Safari 2 fork.
      forEach = function forEach() {
        // ...
      }
    } else {
      // Normal environments.
      forEach = function forEach() {
        // ...
      };
    }
    return forEach;
  }());
}());

// Possible Future Implementation...
(function () {
  // Define the library methods without forking.
  var hasOwnProperty = {}.hasOwnProperty;
  function forEach(iterator, object) {
    // ...
  }
  function fold(iterator, memo, object) {
    // ...
  }
  function isPropertyOf(object, property) {
    // ...
  }

  // Implement `hasOwnProperty` in Safari 2.
  if (typeof hasOwnProperty != 'function') {
    hasOwnProperty = function (property) {
      // ...
    };
  }

  // Use defined library methods to detect `for...in` bugs in legacy engines.
  function Properties() {
    this.toString = 1;
  }
  Properties.prototype.toString = 1;
  if (fold(function (memo) {
    return ++memo;
  }, 0, new Properties) != 1) {
    // Wrap the `forEach` function in IE and Safari 2.
  }
}());