DRY principle - example cluster add calculation

src/message/simple_edits.py

@@ -3,6 +3,7 @@ from message.simple_messages import NoReset, DataChgClickMessage
 import message.common_accessors as common_accessors
 from browser import document
 from model import Sense, Example
+from model.example_clusters import ExampleClusters
 
 
 class QuestionMessage(Message):
@@ -111,12 +112,6 @@ class ExampleClusterAdd(DataChgClickMessage):
     def update_model(self, model):
         example = self.get_arg(0, Example)
         
-        max_example_cluster_num = 0
-        for sense in model.entry.senses:
-            for ex in sense.examples:
-                cnum = ex.get_cluster()
-                if cnum is not None:
-                    max_example_cluster_num = max(max_example_cluster_num, cnum)
-                
+        max_example_cluster_num = ExampleClusters.first_empty_cluster()
         example.set_cluster(max_example_cluster_num + 1)