from ..backend import KeyringBackend


class Keyring(KeyringBackend):
    """
    Keyring that return None on every operation.

    >>> kr = Keyring()
    >>> kr.get_password('svc', 'user')
    """

    priority = -1

    def get_password(self, service, username, password=None):
        pass

    set_password = delete_password = get_password