class_docstr: An abstract class that defines a data source.
class_docstr_tok: ["An","abstract","class","that","defines","a","data","source","."]
code: def camera_ids(self):
      if not self.use_camera_id:
          return tuple()
      return tuple(
          sorted(set([self.get_camera_id(i) for i in self.train_ids]))
      )
  
imports: import abc
  import functools
  import itertools
  from typing import Any, Iterable, Optional, Sequence, Union
  from absl import logging
  from flax import jax_utils
  import jax
  import numpy
  import tensorflow
  from nerfies import camera
  from nerfies import gpath
  from nerfies import image_utils
  from nerfies import tf_camera
  from nerfies import utils
  from tensorflow.python.data.util import nest
label_desc: Use image node_id 16 for calling the DataSource obj's underlying member method code with example usage: obj.camera_ids() and returns: tuple, tuple