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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def surviors_are_inconsistent(survivor_mapping: Mapping[BaseEntity, Set[BaseEntity]]) -> Set[BaseEntity]: """Check that there's no transitive shit going on."""

    victim_mapping = set()
    for victim in itt.chain.from_iterable(survivor_mapping.values()):
        if victim in survivor_mapping:
            victim_mapping.add(victim)
    return victim_mapping