code: def test_compute_variant_stats_for_charts(self):
      expected_keys = [
          "vaf_histograms_by_genotype",
          "indel_sizes",
          "base_changes",
          "qual_histogram",
          "gq_histogram",
          "variant_type_counts",
          "depth_histogram",
          "titv_counts",
      ]
      vis_data = vcf_stats._compute_variant_stats_for_charts(
          [self.variant]
      )
      self.assertCountEqual(
          vis_data.keys(),
          expected_keys,
          msg="vis_data does not have the right keys",
      )
  
imports: import collections
  import json
  import os
  import tempfile
  from absl.testing import absltest
  from absl.testing import parameterized
  import tensorflow
  from deepvariant import testdata
  from deepvariant import vcf_stats
  from third_party.nucleus.io import vcf
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import variant_utils
  from third_party.nucleus.util import variantcall_utils
label_desc: Use image node_id 4 for calling the VcfStatsTest obj's underlying member method code with example usage: obj.test_compute_variant_stats_for_charts() without return types