code: func FilterS(f func(string) bool, sl []string) (result []string) {
  	result = make([]string, 0)
  	for i := range sl {
  		if f(sl[i]) {
  			result = append(result, sl[i])
  		}
  	}
  	return result
  }
docs: // Filter out all strings where the function does not return true