bearer/opts.go
func ExpiresIn(d time.Duration) Option {
	return func(tok *Bearer) error {
		if d != 0 {
			tok.addExpiration = true
			tok.expiresIn = d
		} else {
			tok.addExpiration = false
			tok.expiresIn = 0
		}

		return nil
	}
}
func ExpiresIn(d time.Duration) Option {
	return func(tok *Bearer) error {
		if d != 0 {
			tok.addExpiration = true
			tok.expiresIn = d
		} else {
			tok.addExpiration = false
			tok.expiresIn = 0
		}

		return nil
	}
}
// ExpiresIn is an option that will set the expiration duration generated for
// tokens to the specified duration.