python isinstance is ==

class A():
    pass
class B(A):
    pass

b=B()
print(isinstance(b,B))##True
print(isinstance(b,A))##True
print(type(b) is B)##True is id相同 
print(type(b) == B)##True
print(type(b) is A)##False
print(type(b) == A)##False