action_list : action action_list
                | action

def p_action_list(p):
    """
    action_list : action action_list
                | action
    """
    if len(p) == 3:
        p[0] = p[1] + p[2]
    elif len(p) == 2:
        p[0] = p[1]
    else:
        raise RuntimeError("Invalid production rules 'p_action_list'")