updated contents from Atlas repo

decorators/registration.py

@@ -0,0 +1,31 @@
+# BEGIN REGISTRATION
+
+registry = []  # <1>
+
+def register(func):  # <2>
+    print('running register(%s)' % func)  # <3>
+    registry.append(func)  # <4>
+    return func  # <5>
+
+@register  # <6>
+def f1():
+    print('running f1()')
+
+@register
+def f2():
+    print('running f2()')
+
+def f3():  # <7>
+    print('running f3()')
+
+def main():  # <8>
+    print('running main()')
+    print('registry ->', registry)
+    f1()
+    f2()
+    f3()
+
+if __name__=='__main__':
+    main()  # <9>
+
+# END REGISTRATION