Consider less verbose Action signature

[pedromss]

Just a thought but you introduce 2 types to make the func taken by SetAction a little easier on the eyes:

type CliArgs map[string]commando.ArgValue
type CliFlags flags map[string]commando.FlagValue
SetAction(func(args CliArgs, flags CliFlags) {
   ...   
})

Client code would have easier to read signatures on these actions.

Or event a single struct to hold both:

type Cli struct {
	Args map[string]commando.ArgValue
	Flags map[string]commando.FlagValue
}
SetAction(func(cli Cli) {
   ...   
})