code: def test_unique_reserved_format(self):
      num_reserved_format = len(vcf_constants.RESERVED_FORMAT_FIELDS)
      unique_format_ids = {
          f.id for f in vcf_constants.RESERVED_FORMAT_FIELDS
      }
      self.assertLen(unique_format_ids, num_reserved_format)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import absltest
  from absl.testing import parameterized
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.util import struct_utils
  from third_party.nucleus.util import vcf_constants
label_desc: Use image node_id 3 for calling the VcfConstantsTest obj's underlying member method code with example usage: obj.test_unique_reserved_format() without return types