An example of how to use github.com/looplab/fsm

fsm_example.go

fsm := NewFSM(
    "green",
    Events{
        {Name: "warn", Src: []string{"green"}, Dst: "yellow"},
        {Name: "panic", Src: []string{"yellow"}, Dst: "red"},
        {Name: "panic", Src: []string{"green"}, Dst: "red"},
        {Name: "calm", Src: []string{"red"}, Dst: "yellow"},
        {Name: "clear", Src: []string{"yellow"}, Dst: "green"},
    },
    Callbacks{
        "after_warn": func(e *Event) {
            fmt.Println("after_warn")
        },
    },
)

// will print "green"
fmt.Println(fsm.Current())

err := fsm.Event("warn")
if err != nil {
    fmt.Println(err)
}

// will print "yellow"
fmt.Println(fsm.Current())