code: def __call__(self, x, uttid=None):
      # x: [Time, Dim]
      square_sums = (x**2).sum(axis=0)
      mean = x.mean(axis=0)
  
      if self.norm_means:
          x = np.subtract(x, mean)
  
      if self.norm_vars:
          var = square_sums / x.shape[0] - mean**2
          std = np.maximum(np.sqrt(var), self.std_floor)
          x = np.divide(x, std)
  
      return x
  
file_path: espnet/espnet/transform/cmvn.py
imports: import io
  import h5py
  import kaldiio
  import numpy
label_desc: Use image node_id 3 for calling the UtteranceCMVN obj's underlying member method code with example usage: obj.__call__(x, uttid) and returns: x