add a doc

demo.py

+#!/usr/bin/env python
+# encoding: utf-8
+
+from click2 import *
+
+
+class Demo(AppEventNature):
+    def __init__(self):
+        super(Demo, self).__init__()
+    def action(self, eventName):
+        data = self.data
+        data["who"] = "super-click-zqy"
+        data["context"]["super-context"] = "super-context"
+        super(Demo, self).action(eventName)
+        print (data)
+
+if __name__ == "__main__":
+    d = Demo()
+    d.action(eventName="click")
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