code: function() {
  
  		var binding = this.binding;
  
  		var buffer = this.buffer,
  			stride = this.valueSize,
  
  			originalValueOffset = stride * 3;
  
  		binding.getValue( buffer, originalValueOffset );
  
  		// accu[0..1] := orig -- initially detect changes against the original
  		for ( var i = stride, e = originalValueOffset; i !== e; ++ i ) {
  
  			buffer[ i ] = buffer[ originalValueOffset + ( i % stride ) ];
  
  		}
  
  		this.cumulativeWeight = 0;
  
  	}
docs: remember the state of the bound property and copy it to both accus