created main class

src/app.py

@@ -0,0 +1,23 @@
+import sys
+import gi
+gi.require_version('Gtk', '4.0')
+gi.require_version('Adw', '1')
+from gi.repository import Gtk, Adw
+
+
+class MainWindow(Gtk.ApplicationWindow):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Things will go here
+
+class MyApp(Adw.Application)
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self.connect('activate', self.on_activate)
+
+    def on_activate(self, app):
+        self.win = MainWindow(application=app)
+        self.win.present()
+
+app = MyApp(application_id="com.example.GtkApplication")
+app.run(sys.argv)