class_docstr: Writes InputFeature to TF example file.
code: def __init__(self, filename, is_training):
      self.filename = filename
      self.is_training = is_training
      self.num_features = 0
      self._writer = tf.python_io.TFRecordWriter(filename)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import json
  import math
  import os
  import random
  import mesh_tensorflow
  import mesh_tensorflow.bert.bert
  import mesh_tensorflow.bert.optimization
  import mesh_tensorflow.bert.tokenization
  import six
  from six.moves import range
  import tensorflow.compat.v1
  from tensorflow.compat.v1 import estimator
label_desc: Use image node_id 1 to create a new FeatureWriter object from inherited base classes: object with example: obj = FeatureWriter(filename, is_training)