src/vs/editor/common/model/guidesTextModelPart.ts/GuidesTextModelPart/_getIndentLevelForWhitespaceLine
class GuidesTextModelPart:	private _getIndentLevelForWhitespaceLine(
		offSide: boolean,
		aboveContentLineIndent: number,
		belowContentLineIndent: number
	): number {
		const options = this.textModel.getOptions();

		if (aboveContentLineIndent === -1 || belowContentLineIndent === -1) {
			// At the top or bottom of the file
			return 0;
		} else if (aboveContentLineIndent < belowContentLineIndent) {
			// we are inside the region above
			return 1 + Math.floor(aboveContentLineIndent / options.indentSize);
		} else if (aboveContentLineIndent === belowContentLineIndent) {
			// we are in between two regions
			return Math.ceil(belowContentLineIndent / options.indentSize);
		} else {
			if (offSide) {
				// same level as region below
				return Math.ceil(belowContentLineIndent / options.indentSize);
			} else {
				// we are inside the region that ends below
				return 1 + Math.floor(belowContentLineIndent / options.indentSize);
			}
		}
	}