code: function Prompt(...args) {
    Base.apply(this, args);
    this.opt = args[0],
    this.previousAnswers = args[2];
    this.selected = 0;
    this.paginator = new Paginator();
    this.firstRender = true;
    if (typeof this.opt.placeholder === 'function') {
      this.getPlaceholder = this.opt.placeholder;
    } else if (typeof this.opt.placeholder === 'string') {
      this.getPlaceholder = () => this.opt.placeholder;
    } else {
      this.getPlaceholder = () => 'INSERT HERE';
    }
  
    const events = observe(args[1]);
    const keyDowns = events.keypress.filter(function(e) {
      return e.key.name === 'down';
    }).share();
    const keyUps = events.keypress.filter(function(e) {
      return e.key.name === 'up';
    }).share();
    keyDowns.takeUntil(events.line).forEach(this.onDownKey.bind(this));
    keyUps.takeUntil(events.line).forEach(this.onUpKey.bind(this));
    events.line.forEach(this.onSubmit.bind(this));
    return this;
  }
docs: Constructor
  @return {this} Prompt object