docs: function DoneButton(options) {
          var that;
          that = this;
  
          /**
           * ### DoneButton.button
           *
           * The HTML element triggering node.done() when pressed
           */
          if ('object' === typeof options.button) {
              this.button = options.button;
          }
          else if ('undefined' === typeof options.button) {
              this.button = document.createElement('input');
              this.button.type = 'button';
          }
          else {
              throw new TypeError('DoneButton constructor: options.button must ' +
                                  'be object or undefined. Found: ' +
                                  options.button);
          }
  
          this.button.onclick = function() {
              var res;
              res = node.done();
              if (res) that.disable();
          };
      }