ensure source is always disconnected

animation.py

@@ -20,8 +20,11 @@ class Animation:
         self.plot = plot_func(value)
         plt.suptitle(source.name)
         source.add_callback(self.update)
-        plt.show()
-        source.disconnect()
+        try:
+            plt.show()
+        finally:
+            print("disconnect:", source)
+            source.disconnect()
 
     def update(self, value=None, **kwargs):
         self.plot.set(value)