src/vs/editor/common/model/pieceTreeTextBuffer/pieceTreeBase.ts/PieceTreeBase/deleteNodeHead
class PieceTreeBase:	private deleteNodeHead(node: TreeNode, pos: BufferCursor) {
		const piece = node.piece;
		const originalLFCnt = piece.lineFeedCnt;
		const originalStartOffset = this.offsetInBuffer(piece.bufferIndex, piece.start);

		const newStart = pos;
		const newLineFeedCnt = this.getLineFeedCnt(piece.bufferIndex, newStart, piece.end);
		const newStartOffset = this.offsetInBuffer(piece.bufferIndex, newStart);
		const lf_delta = newLineFeedCnt - originalLFCnt;
		const size_delta = originalStartOffset - newStartOffset;
		const newLength = piece.length + size_delta;
		node.piece = new Piece(
			piece.bufferIndex,
			newStart,
			piece.end,
			newLineFeedCnt,
			newLength
		);

		updateTreeMetadata(this, node, size_delta, lf_delta);
	}