Demonstration of how **= does not follow the data model appropriately

pow_test.py

class PowTest:
    def __init__(self, name):
        self.name = name

    def __ipow__(self, _):
        print(f"{self.name}.__ipow__")
        return NotImplemented

    def __pow__(self, _):
        print(f"{self.name}.__pow__")
        return NotImplemented

    def __rpow__(self, _):
        print(f"{self.name}.__rpow__")
        return NotImplemented

    def __isub__(self, _):
        print(f"{self.name}.__isub__")
        return NotImplemented

    def __sub__(self, _):
        print(f"{self.name}.__sub__")
        return NotImplemented

    def __rsub__(self, _):
        print(f"{self.name}.__rsub__")
        return NotImplemented


class PowTestSub(PowTest):
    pass


A = PowTest("A")
B = PowTestSub("B")

print("Pow binary test ...")
try:
    A ** B
except TypeError:
    pass

print("Sub binary test ...")
try:
    A - B
except TypeError:
    pass

print("Pow augment test ...")
A = PowTest("A")
try:
    A **= B
except TypeError:
    pass

print("Sub augment test ...")
try:
    A -= B
except TypeError:
    pass

Results:

Pow binary test ...
A.__pow__
B.__rpow__
Sub binary test ...
A.__sub__
B.__rsub__
Pow augment test ...
A.__ipow__
Sub augment test ...
A.__isub__
A.__sub__
B.__rsub__