src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts/NotebookCellTextModel/textBuffer
class NotebookCellTextModel:	get textBuffer() {
		if (this._textBuffer) {
			return this._textBuffer;
		}

		const builder = new PieceTreeTextBufferBuilder();
		builder.acceptChunk(this._source);
		const bufferFactory = builder.finish(true);
		const { textBuffer, disposable } = bufferFactory.create(model.DefaultEndOfLine.LF);
		this._textBuffer = textBuffer;
		this._register(disposable);

		this._register(this._textBuffer.onDidChangeContent(() => {
			this._hash = null;
			if (!this._textModel) {
				this._onDidChangeContent.fire('content');
			}
		}));

		return this._textBuffer;
	}