bearer/opts.go
func IssuedAt(enable bool) Option {
	return func(tok *Bearer) error {
		tok.addIssuedAt = enable
		return nil
	}
}
func IssuedAt(enable bool) Option {
	return func(tok *Bearer) error {
		tok.addIssuedAt = enable
		return nil
	}
}
// IssuedAt is an option that toggles whether or not the Issued At ("iat")
// field is generated for the token.