def get_chal_class(class_id):
    """
    Utility function used to get the corresponding class from a class ID.

    :param class_id: String representing the class ID
    :return: Challenge class
    """
    cls = CHALLENGE_CLASSES.get(class_id)
    if cls is None:
        raise KeyError
    return cls

    Utility function used to get the corresponding class from a class ID.

    :param class_id: String representing the class ID
    :return: Challenge class
    
CTFd/plugins/challenges/__init__.py