message: Added #empty to state
diff: @@ -20,6 +20,10 @@ export class State {
  this._state = [];
  }
  + empty() {
  + return (this._state.length === 0);
  + }
  +
  push(obj) {
  this._state.push(obj);
  }
  @@ -28,10 +32,6 @@ export class State {
  this._state.pop();
  }
  - empty() {
  - return (this._state.length === 0);
  - }
  -
  top() {
  return this._state[this._state.length - 1];
  }
  