def mux41(i0, i1, i2, i3):

    def mux_fn(s1, s0):
        d = {(0, 0): i0, (0, 1): i1, (1, 0): i2, (1, 1): i3}
tup = s1, s0
return d[tup]
return mux_fn

def xor2(a, b):
    mux_fn = mux41(0, 1, 1, 0)
return mux_fn(a, b)
2 inputs to a function?