docs: function(callback, safeIteration) {
      var i = 0;
  
      if (safeIteration)
        while (i < this.length && (!(i in this) || callback.call(this[i], this[i], i, this) !== false)) ++i;
      else
        while (i < this.length && callback.call(this[i], this[i], i++, this) !== false);
  
      return this;
    }