helper.go
func Method(m map[string]HandlerFunc) HandlerFunc {
	f := func(ctx *Context) error {
		h, ok := m[ctx.Request.Method]
		if ok {
			return h(ctx)
		}
		ctx.Response.Status = http.StatusMethodNotAllowed
		return nil
	}
	return f
}
func Method(m map[string]HandlerFunc) HandlerFunc {
	f := func(ctx *Context) error {
		h, ok := m[ctx.Request.Method]
		if ok {
			return h(ctx)
		}
		ctx.Response.Status = http.StatusMethodNotAllowed
		return nil
	}
	return f
}
// Method takes one map as a paramater.
// Keys of this map are HTTP method mapping to HandlerFunc(s).