@sig(H/ ("a", "b") >> ("b", "a") )
def swap(tup):
    a, b = tup
    return (b, a)
Create a delegator with a retriever to delegate to.
dataset/ETHPy150Open billpmurphy/hask/hask/Data/Tuple.py/swap--crossover with--dataset/ETHPy150Open twisted/imaginary/imaginary/idea.py/DelegatingRetriever.__init__