How to declare add_attributes in Drupal

Hi guys,

I tried to use your function in my PatternLab and it works properly. I've pasted the file in _twig_components/functions/

Now I'm trying to connect my patterns in Drupal Templates and I have that kind of error message : 
`Unknown add_attributes function in Twig_ExpressionParser-"getFunctionNodeClass()</em>`

What did I forget ?