code: def delta_delta(feat, order=2):
      """
      params:
        feat: a tensor of shape [nframe, nfbank] or [nframe, nfbank, 1]
      return: [nframe, nfbank, 3]
      """
      feat = tf.cond(
          tf.equal(tf.rank(feat), 3),
          true_fn=lambda: feat[:, :, 0],
          false_fn=lambda: feat,
      )
  
      shape = tf.shape(feat)
      # [nframe nfbank*3]
      nframe = shape[0]
      nfbank = shape[1]
      delta = py_x_ops.delta_delta(feat, order=order)
      feat_with_delta_delta = tf.reshape(
          delta, (nframe, nfbank, (order + 1))
      )
      return feat_with_delta_delta
  
file_path: delta/delta/data/feat/speech_ops.py
imports: import numpy
  from absl import logging
  import delta.compat
  from tensorflow.python.ops import gen_audio_ops
  from delta import utils
  from delta.utils.hparam import HParams
  from core.ops import py_x_ops
label_desc: Use image node_id 5 for calling a global function with example usage: delta_delta(feat, order) and returns: feat_with_delta_delta