src/vs/editor/common/model/pieceTreeTextBuffer/pieceTreeBase.ts/PieceTreeBase/iterate
class PieceTreeBase:	iterate(node: TreeNode, callback: (node: TreeNode) => boolean): boolean {
		if (node === SENTINEL) {
			return callback(SENTINEL);
		}

		const leftRet = this.iterate(node.left, callback);
		if (!leftRet) {
			return leftRet;
		}

		return callback(node) && this.iterate(node.right, callback);
	}