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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 get_secret(self, handle, contributor):
 """Retrieve an existing secret's value. :param handle: Secret handle :param contributor: User instance to perform contributor validation, which means that only secrets for the given contributor will be looked up. """

        queryset = self.all()
        if contributor is not None:
            queryset = queryset.filter(contributor=contributor)
        secret = queryset.get(handle=handle)
        return secret.value