    linkView.sendToken(token [, opt, callback])

Send a token along the link. `token` is an SVG element (or Vectorizer element) that will be animated along the link path for `opt.duration` milliseconds (default is 1000ms). The `callback` function will be called once the token reaches the end of the link path.

`opt.direction` specifies whether the animation should be played forwards (`'normal'` - from the link source to target, the default) or backwards (`'reverse'`).

Use `opt.connection` to specify the SVGPathElement for the token to follow. It expects a string selector, e.g. `'.connection'`.

    // Send an SVG circle token along the link.
    var vCircle = V('circle', { r: 7, fill: 'green' });
    link.findView(paper).sendToken(vCircle, { duration: 500, direction: 'reverse' }, function() {
      console.log('animation end');
    });

Note that in the code above, we use the Vectorizer mini-library to create the SVG `circle` element.

See the Petri Net simulator demo for a full working example.