code: function ( a, order, prop, prop2 )
  	{
  		var out = [];
  		var i=0, ien=order.length;
  	
  		// Could have the test in the loop for slightly smaller code, but speed
  		// is essential here
  		if ( prop2 !== undefined ) {
  			for ( ; i<ien ; i++ ) {
  				out.push( a[ order[i] ][ prop ][ prop2 ] );
  			}
  		}
  		else {
  			for ( ; i<ien ; i++ ) {
  				out.push( a[ order[i] ][ prop ] );
  			}
  		}
  	
  		return out;
  	}
docs: Basically the same as _pluck, but rather than looping over `a` we use `order` as the indexes to pick from `a`