code: def test_compute_depth_histogram(self):
      variant_stats_lite = collections.namedtuple(
          "variant_stats_lite", ["depth"]
      )
      variant_stats = [
          variant_stats_lite(depth=100),
          variant_stats_lite(depth=30),
          variant_stats_lite(depth=30),
      ]
      hist = vcf_stats._compute_depth_histogram(variant_stats)
      self.assertEqual(hist, [[30, 2], [100, 1]])
  
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 13 for calling the VcfStatsTest obj's underlying member method code with example usage: obj.test_compute_depth_histogram() without return types