@param fp File handle of the data file whose index is being opened
@param fn BAM/CRAM/etc data file filename
@param fnidx Index filename, or NULL to search alongside @a fn
@return The index, or NULL if an error occurred.
Equivalent to sam_index_load3(fp, fn, fnidx, HTS_IDX_SAVE_REMOTE);
@param fp File handle of the data file whose index is being opened @param fn BAM/CRAM/etc data file filename @param fnidx Index filename, or NULL to search alongside @a fn @return The index, or NULL if an error occurred.
Equivalent to sam_index_load3(fp, fn, fnidx, HTS_IDX_SAVE_REMOTE);