Luckily, this is a solved problem for go.

  func helper(a float64, c chan float64){
      time.Sleep(time.Duration(a) * time.Second)
      c <- a
  }
  
  func clamp(a float64, min float64, max float64) float64 {
      c := make(chan  float64, 3)
      go helper(a, c)
      go helper(min, c)
      go helper(max, c)
      _, out, _ := <-c, <-c, <-c
      return out
  }