class A(object):

    def a1(self):
        """ This is an instance method. """
print('Hello from an instance of A')

@classmethod
def a2(cls):
    """ This a classmethod. """
print('Hello from class A')


class B(object):

    def b1(self):
        print(A().a1())
print(A.a2())
Python с использованием методов из других классов