New action 'call' in Form plugin

Hello all!
I'm newbie in grav and php (and english)). Where i must put my function or class so that new Form action 'call' can run it?
I put public static function in form.php in Form plugin directory but i got 'Crikey!..' error in browser when click submit button.

If you are creating a custom form action, you will need to create a new plugin to add the actual php code. See next docs:

https://learn.getgrav.org/plugins/plugin-tutorial

https://learn.getgrav.org/forms/forms/reference-form-actions#add-your-own-custom-processing-to-a-form

dont modify core plugins, your changes will be lost on update anyway.

Thanks, hugoaf!
But i'm about new action 'call' in core plugin Form, you can see it in the #407 line of code: https://github.com/getgrav/grav-plugin-form/blob/develop/form.php#L407