@param fn Input BAM/BCF/etc filename @param fnidx The input index filename @return The index, or NULL if an error occurred. @note This only works for BCF files. Consider synced_bcf_reader instead which works for both BCF and VCF.
See Implementation
@param fn Input BAM/BCF/etc filename @param fnidx The input index filename @return The index, or NULL if an error occurred. @note This only works for BCF files. Consider synced_bcf_reader instead which works for both BCF and VCF.