javascript - D3 fading SVG path animation -

could please show me how fade out older path segments in d3 svg animation:

http://jsbin.com/zegim/2/edit

this example fading out entire path in 10 seconds, see how path segments (and remain faded). added line:

path.append('svg:animate') .attr('attributename', 'opacity') .attr('from', '1') .attr('to', '0') .attr('dur', 10);

the example same code question: changing speed of d3 path animation http://bl.ocks.org/explunit/6082362

thanks!