Suggestion made by lpottieras a "nice to have" for a future release.

It could be nice that the API considers by default the current directory to find PFN (Path(".").resolve() ) so the users do not have to type that each time it as it can be error-prone.

Example.
./inputs/f.a <-- already exists

rc = ReplicaCatalog()
rc.add_replica(site="local", lfn="f.a") <-- internally check Path(".") / "inputs/"f.a" and throw FileNotFound error if it doesn't exist there ONLY if site is "local"

If pfn was given explicitly, then we use that.