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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 check_auth(self, all_credentials):
 """Update this socket's authentication. Log in or out to bring this socket's credentials up to date with those provided. Can raise ConnectionFailure or OperationFailure. :Parameters: - `all_credentials`: dict, maps auth source to MongoCredential. """

        if all_credentials or self.authset:
            cached = set(itervalues(all_credentials))
            authset = self.authset.copy()

            # Logout any credentials that no longer exist in the cache.
            for credentials in authset - cached:
                auth.logout(credentials.source, self)
                self.authset.discard(credentials)

            for credentials in cached - authset:
                auth.authenticate(credentials, self)
                self.authset.add(credentials)