@staticmethod
def p_available_event_list_optional_list(p):
    """available_event_list_optional_list : available_event_list_optional
                                              | available_event_list_optional available_event_list_optional_list"""
    try:
        p[0] = [p[1]] + p[2]
    except IndexError:
        p[0] = [p[1]]
