src/vs/editor/common/model/bracketPairsTextModelPart/bracketPairsTree/ast.ts/ArrayListAstNode/unprependChild
class ArrayListAstNode:	public unprependChild(): AstNode | undefined {
		this.throwIfImmutable();
		const item = this._children.shift();
		this.handleChildrenChanged();
		return item;
	}