def unpack_input(pipeable):
    """Decorator to place before Pipeable to cause inputs to be unpacked into the Pipeable-decorated function.

    I.e. if you want (a, b) >> func() to correspond to func(a, b), then place this above Pipeable, as follows::

        @unpack_input
        @Pipeable
        def func(a, b):
            pass

    """
    pipeable.unpack_input = True
    return pipeable
