isAvailableChunk = (a, b) => {
	const queue = new Set(b.groupsIterable);
	for (const chunkGroup of queue) {
		if (a.isInGroup(chunkGroup)) continue;
		if (chunkGroup.isInitial()) return false;
		for (const parent of chunkGroup.parentsIterable) {
			queue.add(parent);
		}
	}
	return true;
}
@param {Chunk} a chunk
@param {Chunk} b chunk
@returns {boolean} true, if a is always a parent of b