Craft spears without damaging the knife?

[GalloViking]

Hello survivors, I need some help.

 

I've very recently started modding (yesterday, actually), and made a rather simple spear oriented profession. The profession works fine, and now I'm trying to give it a special trait that allows it to make crafted spears without changing durability on the knife used in the process. Searching through the files, I've found that knife durability reduction is done in Recipe.OnCreate.CreateSpear function, found in the recipecode.lua. How exactly can I edit this function to add a simple exception for my trait?