src/vs/editor/common/model/pieceTreeTextBuffer/pieceTreeTextBuffer.ts/PieceTreeTextBuffer/getRangeAt
class PieceTreeTextBuffer:	public getRangeAt(start: number, length: number): Range {
		const end = start + length;
		const startPosition = this.getPositionAt(start);
		const endPosition = this.getPositionAt(end);
		return new Range(startPosition.lineNumber, startPosition.column, endPosition.lineNumber, endPosition.column);
	}