build/lib/policies.ts/getProperty
function getProperty<T>(qtype: QType<T>, node: Parser.SyntaxNode, key: string): T | undefined {
	const query = new Parser.Query(
		typescript,
		`(
			(pair
				key: [(property_identifier)(string)] @key
				value: ${qtype.Q}
			)
			(#eq? @key ${key})
		)`
	);

	return qtype.value(query.matches(node));
}