  slide.addText("The next slide here", { placeholder: "spoiler" });

    slide = pres.addSlide({ masterName: "SlideWithSpoiler" });

    // Add text, charts, etc. to any placeholder using its `name`
    slide.addText("How sweet the sound!\nThat saved a wretch like me.\nI once was lost, but now was found.\nWas blind, but now I see.", { placeholder: "maincontent" });
    slide.addText("The next slide here", { placeholder: "spoiler" });
    slide.addText("And more text", { placeholder: "spoiler" });

    // 4.