add xml section

part3.py

@@ -0,0 +1,30 @@
+import sys
+import gi
+gi.require_version('Gtk', '4.0')
+gi.require_version('Adw', '1')
+from gi.repository import Gtk, Adw
+
+class MyApp(Adw.Application):
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self.connect('activate', self.on_activate)
+
+    def on_activate(self, app):
+        # Create a Builder
+        builder = Gtk.Builder()
+        builder.add_from_file("test.ui")
+
+        # Obtain the button widget and connect it to a function
+        button = builder.get_object("button1")
+        button.connect("clicked", self.hello)
+
+        # Obtain and show the main window
+        self.win = builder.get_object("main_window")
+        self.win.set_application(self)  # Application will close once it no longer has active windows attached to it
+        self.win.present()
+
+    def hello(self, button):
+        print("Hello")
+
+app = MyApp(application_id="com.example.GtkApplication")
+app.run(sys.argv)