code: def start(self, key):
      s = torch.cuda.Event(enable_timing=True)
      s.record()
      self.start_events[key].append(s)
      return self
  
imports: import collections
  import io
  import json
  import librosa
  import numpy
  import soundfile
  import time
  import torch
  from scipy.io.wavfile import read
  from .text import SOS_TOK, EOS_TOK
label_desc: Use image node_id 2 for calling the CudaTimer obj's underlying member method code with example usage: obj.start(key) and returns: self