src/vs/editor/common/model/pieceTreeTextBuffer/rbTreeBase.ts/TreeNode/constructor
class TreeNode:	constructor(piece: Piece, color: NodeColor) {
		this.piece = piece;
		this.color = color;
		this.size_left = 0;
		this.lf_left = 0;
		this.parent = this;
		this.left = this;
		this.right = this;
	}