package main

import (
	"html/template"
	"os"
)

type (
	Data struct {
		View   View
		Levels []string
	}

	View struct{}
)

func (v View) Flash(lvl string) []interface{} {
	return []interface{}{"hello"}
}

func main() {
	t, err := template.New("tpl").Parse(`{{ define "layout" }}
    {{ block "flash" . }}
        {{ range $level := .Levels }}
            {{ range $.View.Flash . }}
                <div class="alert alert-{{ $level }}" role="alert">
                    {{ . }} <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button>
                </div>
            {{ end }}
        {{ end }}
    {{ end }}

    {{ block "content" .}}{{end}}
{{ end }}
`)

	if err != nil {
		panic(err)
	}

	t2, err := t.Clone()

	if err != nil {
		panic(err)
	}

	_, err = t2.Parse(`{{ block "content" . }}my content{{ end }}`)

	if err != nil {
		panic(err)
	}

	err = t2.ExecuteTemplate(os.Stdout, "layout", Data{View: View{}, Levels: []string{"info", "warning", "success"}})

	if err != nil {
		panic(err)
	}
}