code: def test_ref_block_does_not_densify_to_next_contig():
      vds = hl.vds.read_vds(
          os.path.join(resource("vds"), "1kg_2samples_starts.vds")
      )
      vds = hl.vds.filter_chromosomes(vds, keep=["chr1", "chr2"])
      ref = vds.reference_data
      var = vds.variant_data.filter_entries(False)
      # max out all chr1 refblocks, and truncate all chr2 refblocks so that nothing in chr2 should be densified
      ref = ref.annotate_entries(
          END=hl.if_else(
              ref.locus.contig == "chr1",
              hl.parse_locus_interval(
                  "chr1",
                  reference_genome=ref.locus.dtype.reference_genome,
              ).end.position,
              ref.locus.position,
          )
      )
      vds = hl.vds.VariantDataset(reference_data=ref, variant_data=var)
      mt = hl.vds.to_dense_mt(vds)
      mt = mt.filter_rows(mt.locus.contig == "chr2")
      assert mt.aggregate_entries(hl.agg.count()) == 0
  
imports: import os
  import pytest
  import hail
  from hail.utils import new_temp_file
  from hail.vds.combiner.combine import defined_entry_fields
  from ..helpers import resource, test_timeout, qobtest
label_desc: Use image node_id 30 for calling a global function with example usage: test_ref_block_does_not_densify_to_next_contig() without return types