{{define "string_derive" }}{{ $s := $ }}
// String implements fmt.Stringer.
func ({{ $s.Receiver }} *{{ $s.Name }}) String() string {
    if {{ $s.Receiver }} == nil {
        return "{{ $.Name }}(nil)"
    }
    type Alias {{ $s.Name }}
    return fmt.Sprintf("{{ $s.Name }}%+v", Alias(*{{ $s.Receiver }}))
}
{{- end }}