def p_do_stmt_head(p):
    """do_stmt_head : DO ID "=" expression "," expression
                    | DO ID "=" expression "," expression "," expression"""
    p[0] = ['DO', p[2], p[4], p[6]]
    if len(p) == 9:
        p[0] = p[0] + [p[8]]
    else:
        p[0] = p[0] + [['EXPR', ['LITERAL', '1']]]
