Golang why don't we have a set datastructure [closed]

I’m trying to solve “The go programming lanaguage” exercise #1.4 which requires me to have a set. I can create a set type but why doesn’t the language come with one ? go, having come from google, where guava also originated, why didn’t the language designers opt for adding support for fundamental data structures ? why force your users to create their own implementations for something so basic as a set ?