src/vs/editor/common/model/pieceTreeTextBuffer/pieceTreeBase.ts/PieceTreeBase/getNodeContent
class PieceTreeBase:	private getNodeContent(node: TreeNode) {
		if (node === SENTINEL) {
			return '';
		}
		const buffer = this._buffers[node.piece.bufferIndex];
		const piece = node.piece;
		const startOffset = this.offsetInBuffer(piece.bufferIndex, piece.start);
		const endOffset = this.offsetInBuffer(piece.bufferIndex, piece.end);
		const currentContent = buffer.buffer.substring(startOffset, endOffset);
		return currentContent;
	}