Little fixes and example

Fixed is_forwarded custom filter & created example

examples/custom_filters/is_filter_example.py

@@ -0,0 +1,21 @@
+import telebot
+from telebot import custom_filters
+
+bot = telebot.TeleBot('TOKEN')
+
+
+# Check if message is a reply
+@bot.message_handler(is_reply=True)
+def start_filter(message):
+    bot.send_message(message.chat.id, "Looks like you replied to my message.")
+
+# Check if message was forwarded
+@bot.message_handler(is_forwarded=True)
+def text_filter(message):
+    bot.send_message(message.chat.id, "I do not accept forwarded messages!")
+
+# Do not forget to register filters
+bot.add_custom_filter(custom_filters.IsReplyFilter())
+bot.add_custom_filter(custom_filters.ForwardFilter())
+
+bot.polling(non_stop=True)

telebot/custom_filters.py

@@ -97,7 +97,7 @@ class ForwardFilter(SimpleCustomFilter):
     key = 'is_forwarded'
 
     def check(self, message):
-        return message.forward_from_chat is not None
+        return message.forward_from is not None
 
 class IsReplyFilter(SimpleCustomFilter):
     """