code: def test_get_format(self, field_name, reader, expected):
      if reader is not None:
          reader = mock.Mock()
          reader.field_access_cache.format_field_get_fn.return_value = (
              functools.partial(
                  struct_utils.get_string_field, is_single_field=True
              )
          )
  
      call = variants_pb2.VariantCall()
      variantcall_utils.set_format(call, "GP", [0.1, 0.2, 0.7])
      variantcall_utils.set_format(call, "AD", [55, 3])
      variantcall_utils.set_format(call, "DP", 58)
      variantcall_utils.set_format(call, "GL", [-1, -3, -5.5])
      variantcall_utils.set_format(call, "GT", [0, 1])
      variantcall_utils.set_format(call, "FT", ["LowQual"])
      actual = variantcall_utils.get_format(
          call, field_name, vcf_object=reader
      )
      self.assertEqual(actual, expected)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import functools
  from absl.testing import absltest
  from absl.testing import parameterized
  import mock
  from third_party.nucleus.protos import struct_pb2
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.util import struct_utils
  from third_party.nucleus.util import variantcall_utils
label_desc: Use image node_id 3 for calling the VariantcallUtilsTests obj's underlying member method code with example usage: obj.test_get_format(field_name, reader, expected) without return types