package main
import (
   "fmt"
)
func Contains(sl []string, name string) bool {
   for _, value := range sl {
      if value == name {
         return true
      }
   }
   return false
}
func main() {
   sl := []string{"India", "Japan", "USA", "France"}
   countryToCheck := "Argentina"
   isPresent := Contains(sl, countryToCheck)
   if isPresent {
      fmt.Println(countryToCheck, "is present in the slice named sl.")
   } else {
      fmt.Println(countryToCheck, "is not present in the slice named sl.")
   }
}

Argentina is not present in the slice named sl.

package main
import (
   "fmt"
)
func Contains(sl []string, name string) int {
   for idx, v := range sl {
      if v == name {
         return idx
      }
   }
   return -1
}
func main() {
   sl := []string{"India", "Japan", "USA", "France"}
   countryToCheck := "USA"
   index := Contains(sl, countryToCheck)
   if index != -1 {
      fmt.Println(countryToCheck, "is present in the slice named sl at index", index)
   } else {
      fmt.Println(countryToCheck, "is not present in the slice named sl.")
   }
}

USA is present in the slice named sl at index 2