Add after_execution mechanism to gac100 test.

naive-nlu/tree_nlu/tests/gac_100.py

@@ -668,6 +668,10 @@ def main():
             if result != data['answer']:
                 raise AssertionError('{} is not {}'.format(result, data['answer']))
 
+            if "after_execution" in data:
+                for f in data["after_execution"]:
+                    f(knowledge)
+
         elif example_type == 'text_example':
             affirmation = data['affirmation']
             question = data['question']