Observer.prototype.changed = function() {

  var observers = this.observers;
  var clone = this.clone;
  var target = this.target;

  if (Object.keys(target).length !== Object.keys(clone).length) {
    this.rememberState();
    return true;
  }

  for (var key in target)  if (target[key] !== clone[key]) {
    this.rememberState();
    return true;
  }

  for (key in observers)  if (observers[key].changed()) return true;

  this.rememberState();
  return false;
};

Observer.prototype.changed = function() {
  var observers = this.observers;
  var clone = this.clone;
  var target = this.target;

  if (Object.keys(target).length !== Object.keys(clone).length) this._return(true);
  for (var key in target)  if (target[key] !== clone[key]) this._return(true);
  for (key in observers)  if (observers[key].changed()) return true;
  return this._return(false)
};

Observer.prototype._return = function(value) {
  this.rememberState();
  return value;
};

for (var key in target)  if (target[key] !== clone[key]) this._return(true);