class_docstr: Basic tests for the wrapped DeBruijnGraph class.
code: def test_complex_region(self):
      # There is a heterozygous 9 bp deletion of tandem TGA repeat.
      # "chr20:10,095,379-10,095,500"
      ref_reader = fasta.IndexedFastaReader(testdata.CHR20_FASTA)
      bam_reader = sam.SamReader(testdata.CHR20_BAM)
      region = ranges.parse_literal("chr20:10,095,379-10,095,500")
      ref_seq = ref_reader.query(region)
      reads = list(bam_reader.query(region))
      dbg = debruijn_graph.build(ref_seq, reads, self.dbg_options())
      self.assertIsNotNone(dbg)
      self.assertEqual(44, dbg.kmer_size)
      self.assertLen(dbg.candidate_haplotypes(), 2)
      self.assertIn(ref_seq, dbg.candidate_haplotypes())
  
imports: from absl.testing import absltest
  from absl.testing import parameterized
  from third_party.nucleus.io import fasta
  from third_party.nucleus.io import sam
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
  from deepvariant import testdata
  from deepvariant.protos import realigner_pb2
  from deepvariant.realigner.python import debruijn_graph
label_desc: Use image node_id 9 for calling the DeBruijnGraphWrapTest obj's underlying member method code with example usage: obj.test_complex_region() without return types