code: def _get_reserved_field(field_id, reserved_fields):
      """Returns the desired reserved field.
  
      Args:
        field_id: str. The id of the field to retrieve.
        reserved_fields: list(fields). The reserved fields to search.
  
      Returns:
        The reserved field with the given `field_id`.
  
      Raises:
        ValueError: `field_id` is not a known reserved field.
      """
      matching_fields = [
          field for field in reserved_fields if field.id == field_id
      ]
      if not matching_fields:
          raise ValueError(
              "No reserved field with id `{}`".format(field_id)
          )
      return matching_fields[0]
  
file_path: deepvariant/third_party/nucleus/util/vcf_constants.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import functools
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.util import struct_utils
label_desc: Use image node_id 1 for calling a global function with example usage: _get_reserved_field(field_id, reserved_fields) and returns: matching_fields