1r"""
2
3    Test with a class diagram like this::
4
5           A
6          / \
7         B   C
8        / \ / \
9       E   D   F
10
11"""
12
13
14class A(object):
15    pass
16
17
18class B(A):
19    pass
20
21
22class C(A):
23    pass
24
25
26class D(B, C):
27    pass
28
29
30class E(B):
31    pass
32
33
34class F(C):
35    pass
36