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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 validate_registry_uri_authority(auth: str) -> None: """ Raise an exception if the authority is not a valid ENS domain or a valid checksummed contract address. """

    if is_ens_domain(auth) is False and not is_checksum_address(auth):
        raise ValidationError(f"{auth} is not a valid registry URI authority.")