Lint fixes

src/whitenoise/base.py

@@ -4,11 +4,10 @@
 import re
 import warnings
 from posixpath import normpath
-from django.conf import settings
 from wsgiref.headers import Headers
 from wsgiref.util import FileWrapper
 
-from django.http import Http404
+from django.conf import settings
 
 from .media_types import MediaTypes
 from .responders import IsDirectoryError, MissingFileError, Redirect, StaticFile
@@ -152,15 +151,20 @@ def find_file(self, url):
                 pass
 
         if settings.DEBUG and url.startswith(settings.STATIC_URL):
-            paths = '\n    '.join(self.candidate_paths_for_url(url))
+            paths = "\n    ".join(self.candidate_paths_for_url(url))
             from django.contrib.staticfiles.finders import get_finders
             finders = get_finders()
             app_dirs = []
             for finder in finders:
                 for storage in finder.storages.values():
                     app_dirs.append(storage.location)
-            app_dirs = '\n    '.join(sorted(app_dirs))
-            raise MissingFileError(f"{url} not found. Searched these paths:\n\n    {paths}\n\nApp dirs:\n\n    {app_dirs}")
+            app_dirs = "\n    ".join(sorted(app_dirs))
+            raise MissingFileError(f"""{url} not found. Searched these paths:
+
+    {paths}
+
+App dirs:
+    {app_dirs}""")
 
     def candidate_paths_for_url(self, url):
         for root, prefix in self.directories: