add: sym_closed = SCM_INTERN("closed?");
context: ScmObj Scm_Init_dbd_mysql(void){    ScmModule *mod;    /* Register this DSO to Gauche */    SCM_INIT_EXTENSION(dbd_mysql);    /* Create the module if it doesn't exist yet. */    mod = SCM_MODULE(SCM_FIND_MODULE("dbd.mysql", TRUE));    /* Register classes */    MysqlHandleClass =        Scm_MakeForeignPointerClass(mod, "<mysql-handle>",                                    NULL, mysql_cleanup, 0);    MysqlResClass =        Scm_MakeForeignPointerClass(mod, "<mysql-res>",                                    NULL, mysql_res_cleanup, 0);    /* Register stub-generated procedures */    Scm_Init_dbd_mysqllib(mod);}