How to define an exception hierarchy for domain errors in Python

class DomainError(Exception):
    """Base class for all domain errors."""
    pass

class ValidationError(DomainError):
    """Raised when input data fails validation rules."""
    pass

class NotFoundError(DomainError):
    """Raised when a requested entity does not exist."""
    pass

class PermissionDeniedError(DomainError):
    """Raised when a user lacks permission for an operation."""
    pass

class ConcurrencyError(DomainError):
    """Raised when a conflict occurs due to concurrent modifications."""
    pass

def process_order(order_id):
    if order_id <= 0:
        raise ValidationError(f"Invalid order ID: {order_id}")
    if order_id == 404:
        raise NotFoundError(f"Order {order_id} not found")
    if order_id == 403:
        raise PermissionDeniedError(f"Access denied for order {order_id}")
    if order_id == 409:
        raise ConcurrencyError(f"Order {order_id} was modified elsewhere")

if __name__ == "__main__":
    for order_id in [1, 404, 403, 409, -100]:
        try:
            process_order(order_id)
            print(f"Order {order_id}: processed successfully")
        except DomainError as e:
            print(f"Order {order_id}: {type(e).__name__} - {e}")