class_docstr: Speech task which need generate feat and cmvn
class_docstr_tok: ["Speech","task","which","need","generate","feat","and","cmvn"]
docstr: generate features,
     paths: list or tuple
docstr_tok: ["generate","features",",","paths",":","list","or","tuple"]
code: def generate_feat(self, paths):
      """
      generate features,
         paths: list or tuple
      """
      return NotImplementedError()
  
file_path: delta/delta/data/task/base_task.py
imports: import abc
label_desc: Use image node_id 1 for calling the WavSpeechTask obj's underlying member method code with example usage: obj.generate_feat(paths) and returns: NotImplementedError