code: def D_simple(request):
      if request.param is None:
          return None
      else:
          return muda.deformers.TimeStretch(rate=request.param)
  
imports: from copy import deepcopy
  import re
  import six
  import numpy
  import soundfile
  import jams
  import librosa
  import muda
  import pytest
  import scipy
  from contextlib import contextmanager
label_desc: Use image node_id 13 for calling a global function with example usage: D_simple(request) and returns: None, muda