def METHOD_NAME(self, mac_tag):
    """Verify that a given **binary** MAC (computed by another party)
    is valid.
    Args:
      mac_tag (byte string/byte string/memoryview): the expected MAC of the message.
    Raises:
        ValueError: if the MAC does not match. It means that the message
            has been tampered with or that the MAC key is incorrect.
    """
    secret = get_random_bytes(16)
    mac1 = BLAKE2s.new(digest_bits=160, key=secret, data=mac_tag)
    mac2 = BLAKE2s.new(digest_bits=160, key=secret, data=self.digest())
    if mac1.digest() != mac2.digest():
        raise ValueError("MAC check failed")