'Get an auth instance which can be used to sign a request
using the given signature version.'

def get_auth_instance(self, signature_version, **kwargs):

    cls = altuscli.auth.AUTH_TYPE_MAPS.get(signature_version)
    if (cls is None):
        raise UnknownSignatureVersionError(signature_version=signature_version)
    frozen_credentials = self._credentials.get_frozen_credentials()
    kwargs['credentials'] = frozen_credentials
    auth = cls(**kwargs)
    return auth
