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