showBannerAd() {
    let bannerConfig: AdMobFreeBannerConfig = {
        isTesting: true, // Remove in production
        autoShow: true,
        bannerAtTop: false,
        id: "ca-app-pub-3940256099942544/6300978111"
    };
    this.admobFree.banner.config(bannerConfig);
  
    this.admobFree.banner.prepare().then(() => {
        // success
    }).catch(e => alert(e));
  }

  showInterstitialAd() {
    this.admobFree.interstitial.isReady().then(() => {
      this.admobFree.interstitial.show().then(() => {
      })
        .catch(e =>alert("show "+e));
    })
      .catch(e =>alert("isReady "+e));
  }