This is an enumeration for const creation. Go compiler starts iota from 0 and increments by one for each following constant. The value is determined at compile time rather than run time. Because of this we can't apply iota to expressions which are evaluated at run time.
Program to use iota in const
package main
import "fmt"
const (
Low = 5 * iota
Medium
High
)
func main() {
// Use our iota constants.
fmt.Println(Low)
fmt.Println(Medium)
fmt.Println(High)
}
Try it in Go Playground