docs: def drop_message(self, message):
          """Drop the given message object from the appropriate message list.
  
          Returns True if the message was found, otherwise False."""
  
          for type_ in 'errors', 'warnings', 'notices':
              list_ = getattr(self, type_)
              if message in list_:
                  list_.remove(message)
                  if 'signing_severity' in message:
                      self.signing_summary[message['signing_severity']] -= 1
                  return True
  
          return False