docs: def on_line(client, line):
      """Default handling for incoming lines.
  
      This handler will automatically manage the following IRC messages:
  
        PING:
          Responds with a PONG.
        PRIVMSG:
          Dispatches the PRIVMSG event.
        NOTICE:
          Dispatches the NOTICE event.
        MOTDSTART:
          Initializes MOTD receive buffer.
        MOTD:
          Appends a line to the MOTD receive buffer.
        ENDOFMOTD:
          Joins the contents of the MOTD receive buffer, assigns the result
          to the .motd of the server, and dispatches the MOTD event.
      """
      if line.startswith("PING"):
          client.send("PONG" + line[4:])
          return True
  
      if line.startswith(":"):
          actor, _, line = line[1:].partition(" ")
      else:
          actor = None
      command, _, args = line.partition(" ")
      command = NUMERIC_EVENTS.get(command, command)
  
      parser = PARSERS.get(command, False)
      if parser:
          parser(client, command, actor, args)
          return True
      elif parser is False:
          # Explicitly ignored message
          return True