subpartition_get_letter
subpartition_get_letter(sp),
subpartition_get_letter(sp),
subpartition_get_letter(sp),
subpartition_get_letter(sp),
subpartition_get_letter(sp),
subpartition_get_letter(sp) == 'a' ? "0" : "*",
char subpartition_get_letter(const struct subpartition *);