diff --git a/learnapp.py b/learnapp.py
index 6296332..8e17b6e 100644
--- a/learnapp.py
+++ b/learnapp.py
@@ -29,12 +29,16 @@ class LearnAppException(Exception):
 # ============================================================================
 # helper functions
 # ============================================================================
-async def check_password(try_pw, pw):
+async def _bcrypt_hash(a, b):
     loop = asyncio.get_running_loop()
-    return pw == await loop.run_in_executor(None, bcrypt.hashpw, try_pw.encode('utf-8'), pw)
+    return await loop.run_in_executor(None, bcrypt.hashpw, a.encode('utf-8'), b)
+
+async def check_password(try_pw, pw):
+    return pw == await _bcrypt_hash(try_pw, pw)
+
+async def bcrypt_hash_gen(new_pw):
+    return await _bcrypt_hash(new_pw, bcrypt.gensalt())
 
-def bcrypt_hash_gen(pw):
-    return bcrypt.hashpw(pw.encode('utf-8'), bcrypt.gensalt())
 
 # ============================================================================
 # LearnApp - application logic
@@ -115,14 +119,13 @@ class LearnApp(object):
         logger.info(f'User "{uid}" logged out')
 
     # ------------------------------------------------------------------------
-    # change_password
+    # change_password. returns True if password is successfully changed.
     # ------------------------------------------------------------------------
     async def change_password(self, uid, pw):
         if not pw:
             return False
 
-        loop = asyncio.get_running_loop()
-        pw = await loop.run_in_executor(None, bcrypt_hash_gen, pw)
+        pw = await bcrypt_hash_gen(pw)
 
         with self.db_session() as s:
             u = s.query(Student).get(uid)
diff --git a/serve.py b/serve.py
index 43ca9ca..dcd93ed 100755
--- a/serve.py
+++ b/serve.py
@@ -16,7 +16,6 @@ import functools
 import tornado.ioloop
 import tornado.web
 import tornado.httpserver
-# from tornado import iostream
 
 # this project
 from learnapp import LearnApp
@@ -34,6 +33,7 @@ def admin_only(func):
             func(self, *args, **kwargs)
     return wrapper
 
+
 # ============================================================================
 # WebApplication - Tornado Web Server
 # ============================================================================
@@ -45,7 +45,6 @@ class WebApplication(tornado.web.Application):
             (r'/change_password', ChangePasswordHandler),
             (r'/question',      QuestionHandler),       # renders each question
             (r'/topic/(.+)',    TopicHandler),          # page for exercising a topic
-            # (r'/learn/(.+)',    LearnHandler),          # page for learning a topic
             (r'/file/(.+)',     FileHandler),           # serve files, images, etc
             (r'/',              RootHandler),           # show list of topics
         ]
@@ -159,24 +158,6 @@ class TopicHandler(BaseHandler):
                 name=self.learn.get_student_name(uid),
                 )
 
-# class LearnHandler(BaseHandler):
-#     @tornado.web.authenticated
-#     def get(self, topic):
-#         uid = self.current_user
-
-#         try:
-#             ok = self.learn.start_learning(uid, topic)
-#         except KeyError:
-#             self.redirect('/')
-#         else:
-#             if ok:
-#                 self.render('learn.html',
-#                             uid=uid,
-#                             name=self.learn.get_student_name(uid),
-#                             )
-#             else:
-#                 self.redirect('/')
-
 
 # ----------------------------------------------------------------------------
 # Serves files from the /public subdir of the topics.
@@ -185,8 +166,6 @@ class TopicHandler(BaseHandler):
 class FileHandler(BaseHandler):
     SUPPORTED_METHODS = ['GET']
 
-    # chunk_size = 4 * 1024 * 1024  # serve up to 4 MiB multiple times
-
     @tornado.web.authenticated
     async def get(self, filename):
         uid = self.current_user
@@ -209,18 +188,6 @@ class FileHandler(BaseHandler):
                 self.write(f.read())
                 await self.flush()
 
-                # chunk = f.read(self.chunk_size)
-                # while chunk:
-                #     try:
-                #         self.write(chunk)   # write the chunk to response
-                #         await self.flush()  # flush the current chunk to socket
-                #     except iostream.StreamClosedError:
-                #         break  # client closed the connection
-                #     finally:
-                #         del chunk
-                #         await asyncio.sleep(0)   # 1 nanosecond (hack)
-                #     chunk = f.read(self.chunk_size)
-
 
 # ----------------------------------------------------------------------------
 # respond to AJAX to get a JSON question
@@ -326,6 +293,8 @@ def signal_handler(signal, frame):
         tornado.ioloop.IOLoop.current().stop()
         logging.critical('Webserver stopped.')
         sys.exit(0)
+    else:
+        logging.info('Abort canceled...')
 
 
 # -------------------------------------------------------------------------
@@ -336,8 +305,10 @@ def main():
     argparser = argparse.ArgumentParser(description='Server for online learning. Enrolled students and topics have to be previously configured. Please read the documentation included with this software before running the server.')
     argparser.add_argument('conffile', type=str, nargs='+',
         help='Topics configuration file in YAML format.') # FIXME only one
+    argparser.add_argument('--port', type=int, default=8443,
+        help='Port to be used by the HTTPS server')
     argparser.add_argument('--debug', action='store_true',
-        help='Enable debug messages.')
+        help='Enable debug messages')
     arg = argparser.parse_args()
 
     # --- Setup logging
@@ -380,7 +351,8 @@ def main():
         logging.critical('Certificates cert.pem and privkey.pem not found')
         sys.exit(1)
     else:
-        http_server.listen(8443)
+        http_server.listen(arg.port)
+        logging.info(f'Listening on port {arg.port}.')
 
     # --- run webserver
     logging.info('Webserver running...  (Ctrl-C to stop)')
--
libgit2 0.21.2