Python GTK3 desktop app and Granite App (Elementary OS Desktop)

app_granite.py

import sys
from gi.repository import Granite
from gi.repository import Gtk
from gi.repository import Gio


class LightWindow(Gtk.Dialog):

    def __init__(self):
        super(LightWindow, self).__init__()

        self.set_default_size(400, 300)
        self.set_title('Demo')
        self.set_position(Gtk.WindowPosition.CENTER)


class Application(Granite.Application):
    def __init__(self):
        Gtk.Application.__init__(self,
            flags=Gio.ApplicationFlags.FLAGS_NONE)

        self.license_type = Gtk.License.GPL_3_0

    def do_activate(self):

        light = LightWindow()
        light.set_application (self);
        light.connect("destroy", self.on_quit)
        light.show()

    def do_startup(self):
        Gtk.Application.do_startup(self)

    def do_shutdown(self):
        Gtk.Application.do_shutdown(self)

    def on_quit(self, widget, data):
        self.quit()


if __name__ == '__main__':
    application = Application()
    application.run('', 1)

app_gtk3.py

import sys
from gi.repository import Gtk
from gi.repository import Gio


class ApplicationWindow(Gtk.ApplicationWindow):
    def __init__(self, app):
        Gtk.ApplicationWindow.__init__(self, application=app)
        self.set_default_size(400, 300)
        self.set_title('Demo')
        self.set_default_icon_name('document-properties')
        self.set_position(Gtk.WindowPosition.CENTER)


class Application(Gtk.Application):
    def __init__(self):
        Gtk.Application.__init__(self,
            flags=Gio.ApplicationFlags.FLAGS_NONE)

        self.license_type = Gtk.License.GPL_3_0

    def do_activate(self):
        self.window = ApplicationWindow(app=self)
        self.window.connect('destroy', self.on_quit)
        self.window.show_all()

        self.add_window(self.window)

    def do_startup(self):
        Gtk.Application.do_startup(self)

    def do_shutdown(self):
        Gtk.Application.do_shutdown(self)

    def on_quit(self, widget, data):
        self.quit()


if __name__ == '__main__':
    application = Application()
    application.run(None)

I cannot run the python code for the granite version I get error cannot import name granite. I already installed the python-gi using apt-get on elementaryOS. Any idea what I am missing.

Nevermind I installed the elementary sdk mentioned on https://elementary.io/docs/code/getting-started#developer-sdk and it works now.

great work.