human
Complete this python program:
def _reverse_ordering(ordering_tuple):
assistant
#Here is the Python program you requested.

    """Given an order_by tuple such as `(\-created\, \uuid\)` reverse the
    ordering and return a new tuple, eg. `(\created\, \-uuid\)`.
    """
    def invert(x):
        return (x[1:] if x.startswith(u'-') else (u'-' + x))
    return tuple([invert(item) for item in ordering_tuple])