Could anybody show me when the $input is not set?

[seriquynh]

I ask this question because I don't understand GrahamCampbell's answer in #40133

Could you show me when the $input is not set?

I see it's always set, never null

/**
 * Parse the incoming Artisan command and its input.
 *
 * @param  string  $command
 * @param  array  $parameters
 * @return array
 */
protected function parseCommand($command, $parameters)
{
    if (is_subclass_of($command, SymfonyCommand::class)) {
        $callingClass = true;
        $command = $this->laravel->make($command)->getName();
    }
    if (! isset($callingClass) && empty($parameters)) {
        $command = $this->getCommandName($input = new StringInput($command));
    } else {
        array_unshift($parameters, $command);
        $input = new ArrayInput($parameters);
    }

    return [$command, $input ?? null];
}