change rule and event handle

nonebot/exception.py

@@ -2,6 +2,19 @@
 # -*- coding: utf-8 -*-
 
 
+class IgnoredException(Exception):
+    """
+    Raised by event_preprocessor indicating that
+    the bot should ignore the event
+    """
+
+    def __init__(self, reason):
+        """
+        :param reason: reason to ignore the event
+        """
+        self.reason = reason
+
+
 class PausedException(Exception):
     """Block a message from further handling and try to receive a new message"""
     pass