class_docstr: Expand delta-deltas features from spectrum.
code: def __repr__(self):
      return self.__class__.__name__
  
file_path: fairseq/fairseq/data/audio/feature_transforms/delta_deltas.py
imports: import numpy
  import torch
  from fairseq.data.audio.feature_transforms import AudioFeatureTransform, register_audio_feature_transform
label_desc: Use image node_id 3 for calling the DeltaDeltas obj's underlying member method code with example usage: obj.__repr__() and returns: self