import dataclasses


class JunkComparisonException(BaseException):
    def __str__(self):
        return 'Attempting to perform calculations involving junk values.'


@dataclasses.dataclass
class Junk:
    represents: str | None = None

    def __str__(self):
        return '[{}]'.format(self.represents or 'junk')

    def __repr__(self):
        return self.__str__()

    def __format__(self, format):
        return self.__str__()

    def __add__(self, other):
        return self

    def __radd__(self, other):
        return self

    def __sub__(self, other):
        return self

    def __rsub__(self, other):
        return self