Install mypy and make the minimum changes necessary for it to pass, albeit using --ignore-missing-imports

.gitignore

@@ -15,6 +15,7 @@ media
 # <django-project-name>/staticfiles/
 
 # End of https://www.gitignore.io/api/django
+/.mypy_cache
 /.pytest_cache
 /static
 node_modules

Pipfile

@@ -54,3 +54,4 @@ ptpython = "*"
 pytest-django = "*"
 werkzeug = "*"
 watchdog = "*"
+mypy = "*"

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "dc9793063aa93db7b1b234778ef59289586a037dab65506c477f4e50ca5dc6df"
+            "sha256": "176c601737f4eb5da6b8689846e05d8df8b5b9ef25706fba98ffac6296e3d1d2"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -813,6 +813,14 @@
             ],
             "version": "==4.2.0"
         },
+        "mypy": {
+            "hashes": [
+                "sha256:01cf289838f266ae7c6550c813181ee77d21eac9459dbf067e7a95a0a2db9721",
+                "sha256:bc251cb31bc236d9fe4bcc442c994c45fff2541f7161ee52dc949741fe9ca3dd"
+            ],
+            "index": "pypi",
+            "version": "==0.600"
+        },
         "parso": {
             "hashes": [
                 "sha256:cdef26e8adc10d589f3ec4eb444bd0a29f3f1eb6d72a4292ab8afcb9d68976a6",
@@ -907,6 +915,29 @@
             ],
             "version": "==1.11.0"
         },
+        "typed-ast": {
+            "hashes": [
+                "sha256:0948004fa228ae071054f5208840a1e88747a357ec1101c17217bfe99b299d58",
+                "sha256:25d8feefe27eb0303b73545416b13d108c6067b846b543738a25ff304824ed9a",
+                "sha256:29464a177d56e4e055b5f7b629935af7f49c196be47528cc94e0a7bf83fbc2b9",
+                "sha256:2e214b72168ea0275efd6c884b114ab42e316de3ffa125b267e732ed2abda892",
+                "sha256:3e0d5e48e3a23e9a4d1a9f698e32a542a4a288c871d33ed8df1b092a40f3a0f9",
+                "sha256:519425deca5c2b2bdac49f77b2c5625781abbaf9a809d727d3a5596b30bb4ded",
+                "sha256:57fe287f0cdd9ceaf69e7b71a2e94a24b5d268b35df251a88fef5cc241bf73aa",
+                "sha256:668d0cec391d9aed1c6a388b0d5b97cd22e6073eaa5fbaa6d2946603b4871efe",
+                "sha256:68ba70684990f59497680ff90d18e756a47bf4863c604098f10de9716b2c0bdd",
+                "sha256:6de012d2b166fe7a4cdf505eee3aaa12192f7ba365beeefaca4ec10e31241a85",
+                "sha256:79b91ebe5a28d349b6d0d323023350133e927b4de5b651a8aa2db69c761420c6",
+                "sha256:8550177fa5d4c1f09b5e5f524411c44633c80ec69b24e0e98906dd761941ca46",
+                "sha256:a8034021801bc0440f2e027c354b4eafd95891b573e12ff0418dec385c76785c",
+                "sha256:bc978ac17468fe868ee589c795d06777f75496b1ed576d308002c8a5756fb9ea",
+                "sha256:c05b41bc1deade9f90ddc5d988fe506208019ebba9f2578c622516fd201f5863",
+                "sha256:c9b060bd1e5a26ab6e8267fd46fc9e02b54eb15fffb16d112d4c7b1c12987559",
+                "sha256:edb04bdd45bfd76c8292c4d9654568efaedf76fe78eb246dde69bdb13b2dad87",
+                "sha256:f19f2a4f547505fe9072e15f6f4ae714af51b5a681a97f187971f50c283193b6"
+            ],
+            "version": "==1.1.0"
+        },
         "watchdog": {
             "hashes": [
                 "sha256:7e65882adb7746039b6f3876ee174952f8eaaa34491ba34333ddf1fe35de4162"

lemoncurry/settings/base.py

@@ -11,6 +11,7 @@ https://docs.djangoproject.com/en/1.11/ref/settings/
 """
 
 from os import path
+from typing import List
 
 APPEND_SLASH = False
 
@@ -30,7 +31,7 @@ SECRET_KEY = '6riil57g@r^wprf7mdy((+bs&(6l*phcn9&fd$l0@t-kzj+xww'
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = True
 
-ALLOWED_HOSTS = []
+ALLOWED_HOSTS = []  # type: List[str]
 INTERNAL_IPS = ['127.0.0.1', '::1']
 
 # Settings to tighten up security - these can safely be on in dev mode too,

lemoncurry/urls.py

@@ -13,8 +13,11 @@ Including another URLconf
     1. Import the include() function: from django.conf.urls import url, include
     2. Add a URL to urlpatterns:  url(r'^blog/', include('blog.urls'))
 """
+from typing import Tuple
+
 from django.conf import settings
 from django.urls import include, path
+from django.urls.resolvers import URLPattern
 from django.views.generic import RedirectView
 
 from django.contrib import admin
@@ -47,10 +50,10 @@ urlpatterns = (
     path('sitemap.xml', sitemap.index, maps, name='sitemap'),
     path('sitemaps/<section>.xml', sitemap.sitemap, maps,
          name='django.contrib.sitemaps.views.sitemap'),
-)
+)  # type: Tuple[URLPattern, ...]
 
 if settings.DEBUG:
     import debug_toolbar
-    urlpatterns = (
+    urlpatterns += (
         path('__debug__/', include(debug_toolbar.urls)),
-    ) + urlpatterns
+    )

lemonshort/short_url.py

@@ -1,9 +1,10 @@
 from django.apps import apps
 from django.conf import settings
+from typing import Any, Dict, Type
 
 from .convert import id_to_abc
 
-prefixes = {}
+prefixes = {}  # type: Dict[Type[Any], str]
 
 
 def short_url(entity):