code: def create_features(input_tf, sample_rate_tf, mask_freq):
      """
      Return:
          A tensor of features with size (batch_size, max_time_steps, 80)
      """
  
      features_list = []
      # unstact the features with placeholder
      input_unpack = tf.unstack(input_tf, axis=0)
      for i in range(len(input_unpack)):
          features = _MakeLogMel(input_unpack[i], sample_rate_tf)
          features = tf.reshape(features, shape=[-1, 80])
          features = tf.expand_dims(features, dim=0)
          features_list.append(features)
      features_tf = tf.concat(features_list, axis=0)
      features_tf = features_tf * mask_freq
      return features_tf
  
file_path: cleverhans/cleverhans_v3.1.0/examples/adversarial_asr/tool.py
imports: from tensorflow.python import pywrap_tensorflow
  import numpy
  import tensorflow
  from lingvo.core import asr_frontend
  from lingvo.core import py_utils
label_desc: Use image node_id 3 for calling a global function with example usage: create_features(input_tf, sample_rate_tf, mask_freq) and returns: features_tf