code: function(type, pos, width, height, canvas){
        var ctx = canvas.getCtx();
        height /= 2;
        width /= 2;
        ctx.save();
        ctx.scale(width / height, height / width);
        ctx.beginPath();
        ctx.arc(pos.x * (height / width), pos.y * (width / height), height, 0,
            Math.PI * 2, true);
        ctx.closePath();
        ctx[type]();
        ctx.restore();
      }
docs: /*
  Method: render
  
  Renders an ellipse into the canvas.
  
  Parameters:
  
  type - (string) Possible options are 'fill' or 'stroke'.
  pos - (object) An *x*, *y* object with the position of the center of the ellipse.
  width - (number) The width of the ellipse.
  height - (number) The height of the ellipse.
  canvas - (object) A <Canvas> instance.
  
  Example:
  (start code js)
  NodeHelper.ellipse.render('fill', { x: 10, y: 30 }, 30, 40, viz.canvas);
  (end code)