def authenticate(**credentials):
    """
    If the given credentials are valid, return a User object.
    """
    for backend in get_backends():
        try:
            user = backend.authenticate(**credentials)
        except TypeError:
            # This backend doesn't accept these credentials as arguments. Try the next one.
            continue
        if user is None:
            continue
        # Annotate the user object with the path of the backend.
        user.backend = (backend.__module__, backend.__class__.__name__) % "%s.%s"
        return user
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-0.96/django/contrib/auth/__init__.py/authenticate/swapped operands of `%`