PersistentObjects
PersistentObjects[] gives all persistent objects in all locations in $PersistencePath.
PersistentObjects[patt] gives all persistent objects whose names match the string pattern patt.
PersistentObjects[patt,loc] gives all matching persistent objects in persistence location loc.
PersistentObjects[patt,{loc1,…}] gives all matching persistent objects in all the loci.
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