def nub(it):
    seen = set()
    for v in it:
        h = hash(v)
        if h in seen:
            continue
        seen.add(h)
        yield v
Test releasing a lock that's owned by a different agent.
dataset/ETHPy150Open dossier/dossier.web/dossier/web/label_folders.py/nub--crossover with--dataset/ETHPy150Open viewfinderco/viewfinder/backend/db/test/lock_test.py/LockTestCase.testReleaseOtherOwnedLock