function removeHiddenSlides() {

		if( !config.showHiddenSlides ) {
			Util.queryAll( dom.wrapper, 'section[data-visibility="hidden"]' ).forEach( slide => {
				const parent = slide.parentNode;

				// If this slide is part of a stack and that stack will be
				// empty after removing the hidden slide, remove the entire
				// stack
				if( parent.childElementCount === 1 && /section/i.test( parent.nodeName ) ) {
					parent.remove();
				}
				else {
					slide.remove();
				}

			} );
		}

	}
Removes all slides with data-visibility="hidden". This
is done right before the rest of the presentation is
initialized.

If you want to show all hidden slides, initialize
reveal.js with showHiddenSlides set to true.