function _previousStep() {
    this._direction = 'backward';

    if (this._currentStep === 0) {
      return false;
    }

    var nextStep = this._introItems[--this._currentStep];
    if (typeof (this._introBeforeChangeCallback) !== 'undefined') {
      this._introBeforeChangeCallback.call(this, nextStep.element);
    }

    _showElement.call(this, nextStep);
  }
Go to previous step on intro

@api private
@method _previousStep