How do you debug custom validators from the panel?

Kirby 2 Questions 🤔
1

I’m trying to write some custom validators for my panel and would like some direction on what is used to test them. I tried echo, but that doesn’t seem to work in the panel. Right now I have just a simple proof of concept file.

v::$validators['tst'] = function($value, $mynum) {
	echo("mynum", $mynum);
	return true;
};

Any direction you point me in for debugging would be appreciated.