src/vs/editor/common/model/pieceTreeTextBuffer/pieceTreeBase.ts/PieceTreeBase/startWithLF
class PieceTreeBase:	private startWithLF(val: string | TreeNode): boolean {
		if (typeof val === 'string') {
			return val.charCodeAt(0) === 10;
		}

		if (val === SENTINEL || val.piece.lineFeedCnt === 0) {
			return false;
		}

		const piece = val.piece;
		const lineStarts = this._buffers[piece.bufferIndex].lineStarts;
		const line = piece.start.line;
		const startOffset = lineStarts[line] + piece.start.column;
		if (line === lineStarts.length - 1) {
			// last line, so there is no line feed at the end of this line
			return false;
		}
		const nextLineOffset = lineStarts[line + 1];
		if (nextLineOffset > startOffset + 1) {
			return false;
		}
		return this._buffers[piece.bufferIndex].buffer.charCodeAt(startOffset) === 10;
	}