638 static PyObject *
639 urj_pyc_add_instruction (urj_pychain_t *self, PyObject *args)
640 {
641     char *instname;
642     char *code;
643     char *regname;
644     urj_part_t *part;
645     urj_chain_t *urc = self->urchain;
646 
647     if (!PyArg_ParseTuple (args, "sss", &instname, &code, &regname))
when PyArg_ParseTuple() succeeds
taking False path
648         return NULL;
649     if (!urj_pyc_precheck (urc, UPRC_CBL|UPRC_DET))
when considering value == (int)0 from chain.c:649
taking True path
650         return NULL;
651     part = urj_tap_chain_active_part (urc);
652 
653     if (part == NULL)
654     {
655         if (urj_error_get ())
656         {
657             PyErr_SetString (UrjtagError, urj_error_describe ());
658             urj_error_reset ();
659         }
660         else
661             PyErr_SetString (UrjtagError,
662                              _("liburjtag BUG: unknown urjtag error"));
663         return NULL;
664     }
665 
666     if (urj_part_instruction_define (part, instname, code, regname) == NULL)
667         return urj_py_chkret (URJ_STATUS_FAIL);
668     else
669         return Py_BuildValue ("");
670 }
returning (PyObject*)NULL without setting an exception