Returns whether hardcalls for the variant_numth variant and given allele are represented in a sparse manner that is supported by ReadSparseHardcalls().
HasSparseHardcalls(pgen, variant_num, allele_num = 2L)
True iff the (variant, allele) pair has a sparse representation that can be returned by ReadSparseHardcalls().
Object returned by NewPgen().
Variant index (1-based).
Allele index; 1 corresponds to REF, 2 to the first ALT allele, 3 to the second ALT allele if it exists, etc. Optional, defaults to 2.