simple test case to emulate class methods as function attributes

tests/run/classmethod.pyx

+__doc__ = u"""
+>>> class1.plus1(1)
+2
+>>> class2.plus1(1)
+2
+>>> class3.plus1(1)
+2
+"""
+
+def f_plus(a):
+    return a + 1
+
+class class1:
+    plus1 = f_plus
+
+class class2(object):
+    plus1 = f_plus
+
+cdef class class3:
+    plus1 = f_plus