@classmethod
def _test_scheme_nosalt(cls, scheme):
    """
            Test if the scheme need no salt or raise BadScheme

            :param bytes scheme: A scheme
            :raises BadScheme: if ``scheme` require a salt
        """
    if scheme not in cls.schemes_nosalt:
        cls._raise_bad_scheme(scheme, cls.schemes_nosalt,
            'The scheme %r is only valid with a salt. Valide schemes without salt are %s.'
            )
