Handle change to types.MethodType signature in Python 3.
Handle change to types.MethodType signature in Python 3.

kcarnold/autograd,HIPS/autograd,hips/autograd,barak/autograd,t1m0thy/autograd,melgor/autograd,FighterLYL/autograd,jackkamm/autograd,hips/autograd,HIPS/autograd