code: function(callback, context)
    {
      var callbackContext = context || this;
  
      for (var i = 0; i < this.length; i++)
      {
        var item = this[ i ];
  
        callback.call( callbackContext, item, i );
  
        if ( this[ i ] !== item )
        {
          i--;
        }
      }
  
      return this;
    }
docs: Iterates over each element in this collection and passes the element and
  it's index to the given function. An optional function context can be given.
  
  @method
  @memberof Rekord.Collection#
  @param {Function} callback -
  The function to invoke for each element of this collection passing the
  element and the index where it exists.
  @param {Object} [context] -
  The context to the callback function.
  @return {Rekord.Collection} -
  The reference to this collection.