src/vs/editor/contrib/folding/browser/hiddenRangeModel.ts/HiddenRangeModel/applyMemento
class HiddenRangeModel:	public applyMemento(state: CollapseMemento): boolean {
		if (!Array.isArray(state) || state.length === 0) {
			return false;
		}
		let hiddenRanges: IRange[] = [];
		for (let r of state) {
			if (!r.startLineNumber || !r.endLineNumber) {
				return false;
			}
			hiddenRanges.push(new Range(r.startLineNumber + 1, 1, r.endLineNumber, 1));
		}
		this.applyHiddenRanges(hiddenRanges);
		return true;
	}