code: func Add(name string, fn commandFn) Entrypoint {
  	if _, ok := commands[name]; ok {
  		panic(fmt.Errorf("command with name %q already exists", name))
  	}
  	commands[name] = fn
  	return Entrypoint(name)
  }
docs: // Add adds a new multicall command. name is the command name and fn is the
  // function that will be executed for the specified command. It returns the
  // related Entrypoint.
  // Packages adding new multicall commands should call Add in their init
  // function.