code: def add_command(self, cmd_id, handler):
          
  
          if cmd_id < 0 or cmd_id >= 2**16:
              raise ArgumentError("Command ID in mib block is not a non-negative 2-byte number",
                                  cmd_id=cmd_id, handler=handler)
  
          if cmd_id in self.commands:
              raise ArgumentError("Attempted to add the same command ID twice.", cmd_id=cmd_id,
                                  existing_handler=self.commands[cmd_id],
                                  new_handler=handler)
  
          self.commands[cmd_id] = handler
docs: Add a command to the TBBlock.
  
          The cmd_id must be a non-negative 2 byte number.
          handler should be the command handler