#Usage
##FixedExecutor
exec := executor.NewFixedExecutor(5) // create 5 fixed worker
future := exec.Execute(func() interface{} {
time.Sleep(1 * time.Second)
return "this is my value"
})
if <-future.Done(); future.Error() != nil {
fmt.Println(future.Value().(string)) //this is my value
}else {
//handle error
}
exec.Release()