package main

import "fmt"

func main() {
    var(
        mainString = "Main str "
        already = map[int32]bool{}
        flagAlready bool = false
    )
    for _, value := range mainString{
        if _, ok := already[value]; ok {
            flagAlready = true
            break
        } else { already[value] = true }
    }
    fmt.Printf("%t\n", flagAlready)
}