src/vs/workbench/contrib/mergeEditor/browser/model/lineRange.ts/LineRange/join
class LineRange:	public join(other: LineRange): LineRange {
		return new LineRange(Math.min(this.startLineNumber, other.startLineNumber), Math.max(this.endLineNumberExclusive, other.endLineNumberExclusive) - this.startLineNumber);
	}