type MyStruct struct {
    FieldA string `pongo2:"uh"`
    FieldB string `pongo2:"yeah"`
}

type MyStruct struct {
    fieldA string
}

// GetNamedField implements NamedFieldResolver
func (s MyStruct) GetNamedField(s string) (interface{}, error) {
    switch s {
    case "uh":
        return s.fieldA, nil
    case "yeah":
        return "YEAH!", nil
    default:
        return nil, pongo2.ErrNoSuchField
     }
}

// GetNamedField implements IndexedFieldResolver
func (s MyStruct) GetIndexedField(s int) (interface{}, error) {
    switch s {
    case 0:
        return s.fieldA, nil
    case 1:
        return "YEAH!", nil
    default:
        return nil, pongo2.ErrNoSuchField
    }
}