class CoreValidationError(Exception):
    def __init__(self, exc=None):
        self.message = exc or "Validation error"

    def __str__(self):
        return self.message


class CoreDBError(Exception):
    def __init__(self, exc=None):
        self.message = exc or "Data processing error"

    def __str__(self):
        return self.message


class GenericError(Exception):
    def __init__(self, status_code=200, exc=None):
        self.message = exc or "Data processing error"
        self.status_code = status_code

    def __str__(self):
        return self.message