human
I am working on the file "Section 1 - Core Python/Chapter 09 - Classes & OOPS/OOPs Fundamentals - ABC.ipynb".
The first task is:
NOTE  

issubclass: Return true if class is a subclass (direct, indirect or virtual) of classinfo. A class is considered a subclass of itself. classinfo may be a tuple of class objects, in which case every entry in classinfo will be checked. In any other case, a TypeError exception is raised.

isinstance: Return true if the object argument is an instance of the classinfo argument, or of a (direct, indirect or virtual) subclass thereof. Also return true if classinfo is a type object (new-style class) and object is an object of that type or of a (direct, indirect or virtual) subclass thereof. If object is not a class instance or an object of the given type, the function always returns false. If classinfo is a tuple of class or type objects (or recursively, other such tuples), return true if object is an instance of any of the classes or types. If classinfo is not a class, type, or tuple of classes, types, and such tuples, a TypeError exception is raised.

Registering the child class
Can you write Python program for it?
 What is a the Python program you requested?
assistant
#Here is the Python program you requested.

from abc import ABCMeta, abstractmethod

class Mammal(metaclass=ABCMeta):
    
    @abstractmethod
    def eyes(self, val):
        raise NotImplementedError()

    def hair(self):
        print("hair")
    
    def neocortex(self):
        """a part of the cerebral cortex concerned with sight and hearing in mammals, 
        regarded as the most recently evolved part of the cortex."""
        print("neocortex")
    
class Human:
    def eyes(self, val):
        print("human eyes: ", val)

Mammal.register(Human)
print ('Subclass:', issubclass(Human, Mammal))
c = Human()
print ('Instance:', isinstance(c, Mammal))
c.eyes("Hazel")