Cypclass test distutil & doctest: type inference

nogil_test/cypclass_test_type_inference.pyx

+# mode: run
+# distutils: language=c++
+# distutils: extra_compile_args=-std=c++11
+# tag: cpp
+
 cdef cypclass SomeMemory:
     int a
 
@@ -17,6 +22,12 @@ cdef cypclass SomeSubMemory(SomeMemory):
     int b
 
 cpdef bag():
+    """
+    >>> bag()
+    28
+    4
+    7
+    """
     o1 = SomeMemory()
     o2 = SomeMemory(4)
     o3 = SomeSubMemory(3)