docs: function(callback, properties, values, equals)
    {
      var where = createWhere( properties, values, equals );
  
      for (var i = 0; i < this.length; i++)
      {
        var item = this[ i ];
  
        if ( where( item ) )
        {
          callback.call( this, item, i );
  
          if ( this[ i ] !== item )
          {
            i--;
          }
        }
      }
  
      return this;
    }