def identity(*args):
    """Identity function.

    Accepts any positional arguments, and returns them.

    Packs into a tuple if there is more than one.

    Example::

        assert identity(1, 2, 3) == (1, 2, 3)
        assert identity(42) == 42
        assert identity() is None
    """
    if not args:
        return None
    return args if len(args) > 1 else args[0]