// safe Objecs.keys, found at
// http://whattheheadsaid.com/2010/10/a-safer-object-keys-compatibility-implementation
Object.keys = Object.keys || (function () {
  var hasOwnProperty = Object.prototype.hasOwnProperty,
    hasDontEnumBug = !{toString:null}.propertyIsEnumerable("toString"),
    DontEnums = [
      'toString',
      'toLocaleString',
      'valueOf',
      'hasOwnProperty',
      'isPrototypeOf',
      'propertyIsEnumerable',
      'constructor'
    ],
    DontEnumsLength = DontEnums.length;

  return function (o) {
    if (typeof o != "object" && typeof o != "function" || o === null)
      throw new TypeError("Object.keys called on a non-object");

    var result = [];
    for (var name in o) {
      if (hasOwnProperty.call(o, name)) result.push(name);
    }

    if (hasDontEnumBug) {
      for (var i = 0; i < DontEnumsLength; i++) {
        if (hasOwnProperty.call(o, DontEnums[i])) result.push(DontEnums[i]);
      }
    }

    return result;
  };
})();

// safe isArray, found at
// http://perfectionkills.com/instanceof-considered-harmful-or-how-to-write-a-robust-isarray/
function isArray(o) {
  return Object.prototype.toString.call(o) === '[object Array]';
}