code: function(options) {
        options = options || { };
  
        this.set('radius', options.radius || 0);
        this.callSuper('initialize', options);
  
        var diameter = this.get('radius') * 2;
        this.set('width', diameter).set('height', diameter);
      }
docs: Constructor
  @method initialize
  @param {Object} [options] Options object
  @return {fabric.Circle} thisArg