Not being careful with goroutines and loop variables

s := []int{1, 2, 3}

for _, i := range s {
  go func() { // This is a closure and when it access `i` is not guaranteed
    fmt.Print(i)
  }()
}

s := []int{1, 2, 3}

for _, i := range s {
  // this variable is now local to each scope
  val := i
  go func() {
    fmt.Print(val)
  }()
}

s := []int{1, 2, 3}

for _, i := range s {
  // we pass the value as a parameter so it is evaluated immediately
  go func(val int) {
    fmt.Print(val)
  }(i)
}