class_docstr: Test the functionality of the VcfHeaderCache class.
code: def test_valid_info_set_funcs(self, field_name):
      fn = self.cache.info_field_set_fn(field_name)
      self.assertTrue(callable(fn))
  
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 etils import epath
  from third_party.nucleus.io import vcf
  from third_party.nucleus.protos import reference_pb2
  from third_party.nucleus.protos import struct_pb2
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 3 for calling the VcfHeaderCacheTests obj's underlying member method code with example usage: obj.test_valid_info_set_funcs(field_name) without return types