diff --git a/aprendizations/learnapp.py b/aprendizations/learnapp.py
index 0a8a66f..6a4050a 100644
--- a/aprendizations/learnapp.py
+++ b/aprendizations/learnapp.py
@@ -31,11 +31,11 @@ async def _bcrypt_hash(a, b):
                                       a.encode('utf-8'), b)
 
 
-async def check_password(try_pw, pw):
+async def check_password(try_pw: str, pw: str) -> bool:
     return pw == await _bcrypt_hash(try_pw, pw)
 
 
-async def bcrypt_hash_gen(new_pw):
+async def bcrypt_hash_gen(new_pw: str):
     return await _bcrypt_hash(new_pw, bcrypt.gensalt())
 
 
@@ -75,7 +75,10 @@ class LearnApp(object):
         for c in config_files:
             self.populate_graph(c)
 
-        self.factory = self.make_factory()    # for all questions all topics
+        # factory is a dict with question generators for all topics
+        self.factory = self.make_factory()    # {'qref': QFactory()}
+
+        # if graph has topics that are not in the database, add them
         self.db_add_missing_topics(self.deps.nodes())
 
         if check:
@@ -83,14 +86,19 @@ class LearnApp(object):
 
     # ------------------------------------------------------------------------
     def sanity_check_questions(self):
-        for qref, q in self.factory.items():
-            logger.info(f'Generating {qref}...')
+        def check_question(qref, q):
+            logger.debug(f'Generating {qref}...')
             try:
                 q.generate()
             except Exception as e:
                 logger.error(f'Sanity check failed in "{qref}"')
                 raise e
 
+        logger.info('Starting sanity checks...')
+        for qref, q in self.factory.items():
+            check_question(qref, q)
+        logger.info('Sanity checks passed.')
+
     # ------------------------------------------------------------------------
     # login
     # ------------------------------------------------------------------------
@@ -226,11 +234,13 @@ class LearnApp(object):
     # ------------------------------------------------------------------------
     def db_add_missing_topics(self, topics):
         with self.db_session() as s:
-            dbtopics = [t[0] for t in s.query(Topic.id)]  # get topics from DB
-            missing_topics = [Topic(id=t) for t in topics if t not in dbtopics]
-            if missing_topics:
-                s.add_all(missing_topics)
-                logger.info(f'Added {len(missing_topics)} new topics')
+            new_topics = [Topic(id=t) for t in topics
+                          if (t,) not in s.query(Topic.id)]
+
+            if new_topics:
+                s.add_all(new_topics)
+                logger.info(f'Added {len(new_topics)} new topics to the '
+                            f'database')
 
     # ------------------------------------------------------------------------
     # setup and check database
diff --git a/aprendizations/questions.py b/aprendizations/questions.py
index 06df2d5..30a16d4 100644
--- a/aprendizations/questions.py
+++ b/aprendizations/questions.py
@@ -121,7 +121,7 @@ class QuestionRadio(Question):
 
     # ------------------------------------------------------------------------
     # can return negative values for wrong answers
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
 
         if self['answer'] is not None:
@@ -187,7 +187,7 @@ class QuestionCheckbox(Question):
 
     # ------------------------------------------------------------------------
     # can return negative values for wrong answers
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
 
         if self['answer'] is not None:
@@ -234,7 +234,7 @@ class QuestionText(Question):
         self['correct'] = [str(a) for a in self['correct']]
 
     # ------------------------------------------------------------------------
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
 
         if self['answer'] is not None:
@@ -260,7 +260,7 @@ class QuestionTextRegex(Question):
             })
 
     # ------------------------------------------------------------------------
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
         if self['answer'] is not None:
             try:
@@ -291,7 +291,7 @@ class QuestionNumericInterval(Question):
             })
 
     # ------------------------------------------------------------------------
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
         if self['answer'] is not None:
             lower, upper = self['correct']
@@ -331,7 +331,7 @@ class QuestionTextArea(Question):
         self['correct'] = path.join(self['path'], self['correct'])   # FIXME
 
     # ------------------------------------------------------------------------
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
 
         if self['answer'] is not None:  # correct answer and parse yaml ouput
@@ -368,7 +368,7 @@ class QuestionInformation(Question):
 
     # ------------------------------------------------------------------------
     # can return negative values for wrong answers
-    def correct(self):
+    def correct(self) -> None:
         super().correct()
         self['grade'] = 1.0  # always "correct" but points should be zero!
 
diff --git a/aprendizations/serve.py b/aprendizations/serve.py
index 4e78f93..d58dda4 100644
--- a/aprendizations/serve.py
+++ b/aprendizations/serve.py
@@ -96,12 +96,10 @@ class RankingsHandler(BaseHandler):
     def get(self):
         uid = self.current_user
         rankings = self.learn.get_rankings(uid)
-        # performance = self.learn.get_performance()
         self.render('rankings.html',
                     uid=uid,
                     name=self.learn.get_student_name(uid),
                     rankings=rankings)
-                    # performance=performance)
 
 
 # ----------------------------------------------------------------------------
--
libgit2 0.21.2