code: func OptFieldTypeDefault() FieldOption {
  	return func(fo *FieldOptions) error {
  		if fo.Type != "" {
  			return errors.Errorf("field type is already set to: %s", fo.Type)
  		}
  		fo.Type = FieldTypeSet
  		fo.CacheType = DefaultCacheType
  		fo.CacheSize = DefaultCacheSize
  		return nil
  	}
  }
docs: // OptFieldTypeDefault is a functional option on FieldOptions
  // used to set the field type and cache setting to the default values.