Please check the simple code below:

```py
def extract_class_from_func(func_var):
    # should return class of the func_var
    return ...

class A:
     def m(self):
         print(self, "m")

func_var = A.m

# This check should succeed
assert A == extract_class_from_func(func_var)

```

Please help me in implementing method `extract_class_from_func`