Silly question, what's the difference between expandpermissiontree and readrelationships? My usecase: I have a permission that requires writing two relationships to set. That works great and is easy to manage. However, I also need to be able to sync an external system to spicedb on a regular basis. So, I have something like: type2:id2#rel1@type1:id1 type3:id3#rel2@type2:id2 What's the most efficient way to query all these pairs of relationships, so I can check them against the external system and sync as needed (add/remove pairs)?