Drupal 8.x

Hello,

I'm in the process of migrating a site from drupal 7 to drupal 8 and I'm having a problem with where or how to implement functions I had in my template.php file.

For example in drupal 7 I have this function in my template.php file:

function some_function($var1, $var2){
print $var1 . $var2;
}

I call the function from a template file like this:

<?php some_function('Hello', 'World'); ?>

How and where would I implement something similar in Drupal 8.

Can anyone point me in the right direction to change the displayed text in an entity reference field after I have selected from the auto complete, I ve managed to change what is displayed in the auto complete, now I want to add that change to the actual entity reference field, looking for a tutorial or guidance to learn from

Thanks

I have create a form using taxonomy

Hr_taxonomy_form

And i give privilege to role HR to access Taxonomy.but when user login with role HR can't access taxonomy page.Why?please help me

I need to add custom maintenance page twig file in Drupal 8 so that I can print some block region for example header image same as page.html.twig. I also used maintenance-page--offline.html.twig but that also does not work for me.

Hey,

I want to do a custom validation for a field in some of my webforms.
I came across this code:
https://www.drupal.org/docs/8/modules/webform/webform-cookbook/how-to-add-custom-validation-to-a-webform-element

this is the data from the webform devel
the field I want to do the validate on id calle `idno` 

I don't understand:
1.what are the values: