code: function (x, y, rx, ry) {
      return new BVG('ellipse', x.constructor.name === 'Object' ? x : {
        x: x,
        y: y,
        rx: rx,
        ry: ry
      }, function (tag, data) {
        tag.setAttribute('cx', data.x);
        tag.setAttribute('cy', data.y);
        tag.setAttribute('rx', data.rx);
        tag.setAttribute('ry', data.ry);
      });
    }
docs: ### `bvg.ellipse(cx, cy, rx, ry)`
  Create a ellipse centred on `(cx, cy)` with radii `rx` and `ry`.
  
  ```Javascript
  var ellipse = bvg.ellipse(100, 100, 200, 180);
  ```