def get_class_name_attr(class_obj):
    """
    Given a class object returns attribute that contains the full name or None.

    :param class_obj: Class object (Class)
    :return: full name attr or None (str/None)
    """
    cl_full_name = None
    for key in class_obj.__dict__:
        if 'full_name' in key:
            cl_full_name = key
            break
    return cl_full_name