def METHOD_NAME(self) -> Optional[Dict[str, Union[bool, int, str]]]:
    METHOD_NAME: Dict[str, Union[bool, int, str]] = {}
    if self.max_items:
        METHOD_NAME["max_items"] = self.max_items
        METHOD_NAME["min_items"] = self.min_items or 0
    if self.min_items:
        METHOD_NAME["min_items"] = self.min_items
    if self.unique_items:
        METHOD_NAME["unique"] = True
    return METHOD_NAME or None