Add example of order_children method in example1

Author: dgarros

examples/example1/main.py

@@ -5,6 +5,20 @@
 from backend_c import BackendC
 
 
+from dsync import Diff
+
+
+class MyDiff(Diff):
+    """Custom Diff class to control the order of the site objects"""
+
+    @classmethod
+    def order_children_site(cls, children):
+        """Return the site children ordered in alphabetical order."""
+        keys = sorted(children.keys(), reverse=False)
+        for key in keys:
+            yield children[key]
+
+
 def main():
     """Demonstrate DSync behavior using the example backends provided."""
     # pylint: disable=invalid-name
@@ -18,7 +32,7 @@ def main():
     c = BackendC()
     c.load()
 
-    diff_a_b = a.diff_to(b)
+    diff_a_b = a.diff_to(b, diff_class=MyDiff)
     diff_a_b.print_detailed()
 
     a.sync_to(b)