Use __data__ attributes with native functions apart from when __data__ needs
replacing (such as in the list append and concatenation functions).
1deff(x): 2defg(y,x=x): 3while1: 4defh(z,x=x,y=y): 5returnx,y,z,a 6a=4# not available for h, available in Python 7returnh 8returng 9 10result=f(1)(2)(3) 11assertresult==(1,2,3,4)