code: func OptFieldTypeInt(min, max int64) FieldOption {
  	return func(fo *FieldOptions) error {
  		if fo.Type != "" {
  			return errors.Errorf("field type is already set to: %s", fo.Type)
  		}
  		if min > max {
  			return ErrInvalidBSIGroupRange
  		}
  		fo.Type = FieldTypeInt
  		fo.Min = min
  		fo.Max = max
  		return nil
  	}
  }
docs: // OptFieldTypeInt is a functional option on FieldOptions
  // used to specify the field as being type `int` and to
  // provide any respective configuration values.