app_urls.py

from django.urls import path

from . import views

urlpatterns = [
    path('', views.index, name='index'),
]

app_views.py

from django.http import HttpResponse


def index(request):
    return HttpResponse("Hello, world. You're at the app index.")

techface_urls.py

from django.contrib import admin
from django.urls import include, path

urlpatterns = [
    path('app/', include('app.urls')),
    path('admin/', admin.site.urls),
]