Function borrow_meta 

pub exec fn borrow_meta<'a, M: AnyFrameMeta + Repr<MetaSlotStorage>>(
    ptr: ReprPtr<MetaSlotStorage, M>,
    Tracked(points_to): Tracked<&'a PointsTo<MetaSlot>>,
    Tracked(metadata_perms): Tracked<&'a MetadataPerms>,
    Tracked(repr_perm): Tracked<&'a M::ReprPerm>,
) -> res : &'a M

requires

typed_meta_wf::<M>(*points_to, *metadata_perms, *repr_perm),

ptr.addr() == points_to.addr(),

ensures

*res == typed_meta_value::<M>(*metadata_perms, *repr_perm),