Empty checks for empty list should not be done by comparing lengths and in the teamvideo model a part of code ( a for loop at https://github.com/8planes/mirosubs/blob/master/apps/teams/models.py#L356) seem to be placed at wrong indent.

gistfile2.txt

pythonic_list_empty_checks.patch

diff --git a/apps/teams/models.py b/apps/teams/models.py
index 014b7e1..c3d185d 100644
--- a/apps/teams/models.py
+++ b/apps/teams/models.py
@@ -293,7 +293,7 @@ class TeamVideo(models.Model):
                 team_video=self,
                 subtitle_language_0__language=lang0,
                 language_1=lang1)
-        tvlp = None if len(tvlps) == 0 else tvlps[0]
+        tvlp = None if not tvlps else tvlps[0]
         if not tvlp and percent_complete != -1:
             tvlp = TeamVideoLanguagePair(
                 team_video=self,
@@ -314,9 +314,7 @@ class TeamVideo(models.Model):
 
     def _update_tvlp_for_languages(self, lang0, lang1, langs):
         sl0_list = langs.get(lang0, [])
-        sl1_list = langs.get(lang1, [])
-        if len(sl1_list) == 0:
-            sl1_list = [None]
+        sl1_list = langs.get(lang1, [None])
         for sl0 in sl0_list:
             for sl1 in sl1_list:
                 self._update_team_video_language_pair(lang0, sl0, lang1, sl1)
@@ -350,11 +348,9 @@ class TeamVideo(models.Model):
         langs = self.video.subtitle_language_dict()
 
         for lang in lang_code_list:
-            sl1_list = langs.get(lang, [])
-            if len(sl1_list) == 0:
-                sl1_list = [None]
-                for sl1 in sl1_list:
-                    self._update_team_video_language_pair(sl.language, sl, lang, sl1)
+            sl1_list = langs.get(lang, [None])
+            for sl1 in sl1_list:
+                self._update_team_video_language_pair(sl.language, sl, lang, sl1)
         for sl0 in self.video.subtitlelanguage_set.all():            
             self._update_team_video_language_pair(sl0.language, sl0, sl.language, sl)
 
diff --git a/apps/widget/base_rpc.py b/apps/widget/base_rpc.py
index e5ff654..94879fb 100644
--- a/apps/widget/base_rpc.py
+++ b/apps/widget/base_rpc.py
@@ -79,7 +79,7 @@ class BaseRpc:
         updated = packet['updated']
         inserted = packet['inserted']
 
-        if len(deleted) == 0 and len(inserted) == 0 and len(updated) == 0:
+        if not (deleted or inserted or updated):
             return
         for d in deleted:
             subtitle_set.remove(subtitle_set.get(subtitle_id=d['subtitle_id']))