bearer/opts.go
func Scope(scopes ...string) Option {
	return func(tok *Bearer) error {
		if len(scopes) > 0 {
			return Claim("scope", strings.Join(scopes, " "))(tok)
		}
		return nil
	}
}
func Scope(scopes ...string) Option {
	return func(tok *Bearer) error {
		if len(scopes) > 0 {
			return Claim("scope", strings.Join(scopes, " "))(tok)
		}
		return nil
	}
}
// Scope is an option that adds a Scope ("scope") field to generated tokens.
// Scopes are joined with a space (" ") separator.