sync with Atlas repo

interfaces/diamond.py

@@ -0,0 +1,19 @@
+class A:
+    def ping(self):
+        print('ping:', self)
+
+
+class B(A):
+    def pong(self):
+        print('pong:', self)
+
+
+class C(A):
+    def pong(self):
+        print('PONG:', self)
+
+
+class D(B, C):
+    def pingpong(self):
+        super().ping()
+        super().pong()