src/vs/editor/common/model/bracketPairsTextModelPart/bracketPairsTree/ast.ts/PairAstNode/flattenLists
class PairAstNode:	public flattenLists(): PairAstNode {
		return PairAstNode.create(
			this.openingBracket.flattenLists(),
			this.child && this.child.flattenLists(),
			this.closingBracket && this.closingBracket.flattenLists()
		);
	}