def p_if_stmt(p):
    """if_stmt : IF OPEN_PAREN expression CLOSE_PAREN maybe_nline suite
               | if_stmt ELSEIF OPEN_PAREN expression CLOSE_PAREN maybe_nline suite """
    if len(p) == 7:
        p[0] = ['IF_EXPR']
        p[0].append(p[3])
        p[0].append(p[6])
        p[0].append([])
    else:
        p[0] = p[1]
        p[0][3].append([p[4], p[7]])
