new file mode 100644
--- /dev/null
+++ b/examples/trac/wiki-macros/HelloWorld.py
@@ -0,0 +1,15 @@
+"""Example macro."""
+from trac.util import escape
+
+def execute(hdf, txt, env):
+    # Currently hdf is set only when the macro is called
+    # From a wiki page
+    if hdf:
+        hdf['wiki.macro.greeting'] = 'Hello World'
+        
+    # args will be `None` if the macro is called without parenthesis.
+    args = txt or 'No arguments'
+
+    # then, as `txt` comes from the user, it's important to guard against
+    # the possibility to inject malicious HTML/Javascript, by using `escape()`:
+    return 'Hello World, args = ' + escape(args)