def UriFuncForListInstanceRelatedObjects(resource):
  """UriFunc for listing instance-group related subresources.

  Function returns field with URI for objects being subresources of
  instance-groups, with instance fields. Works for list-instances and
  instance-configs list commands.

  Args:
    resource: instance-group subresource with instance field

  Returns:
    URI of instance
  """
  return resource.instance