class MemoryError(Exception):
    pass


class AddressError(MemoryError):
    def __init__(self, index=None):
        super().__init__(self)
        if not index:
            self.errorinfo = "None"
        else:
            self.errorinfo = str(hex(index))

    def __str__(self):
        return self.errorinfo

class OutOfMemory(MemoryError):
    pass

class InstructionError(Exception):
    pass


class InvalidInstruction(InstructionError):
    pass


class BadOperand(InstructionError):
    pass