Method Resolution Order in Python

mro.py

"""
Case 1: B, C are connected to A
"""

class A(object): pass
class B(A): pass
class C(A): pass
class D(B, C): pass

assert D.__mro__ == (D, B, C, A, object)

"""
Case 2: G, H have similar orderings
"""

class E(object): pass
class F(object): pass
class G(F, E): pass
class H(F, E): pass
class I(G, H): pass

assert I.__mro__ == (I, G, H, F, E, object)

"""
Case 3: L, M have bad orderings
"""

class J(object): pass
class K(object): pass
class L(J, K): pass
class M(K, J): pass

try:
    class N(L, M): pass
except TypeError:
    print('Cannot get MRO for (J, K) and (K, J)')