code: def writeint2dnorm(filename, Intensity, Error=None):
      
      whattosave = {'Intensity': Intensity}
      if Error is not None:
          whattosave['Error'] = Error
      if filename.upper().endswith('.NPZ'):
          np.savez(filename, **whattosave)
      elif filename.upper().endswith('.MAT'):
          scipy.io.savemat(filename, whattosave)
      else:  # text file
          np.savetxt(filename, Intensity)
          if Error is not None:
              name, ext = os.path.splitext(filename)
              np.savetxt(name + '_error' + ext, Error)
docs: Save the intensity and error matrices to a file
  
      Inputs
      ------
      filename: string
          the name of the file
      Intensity: np.ndarray
          the intensity matrix
      Error: np.ndarray, optional
          the error matrix (can be ``None``, if no error matrix is to be saved)
  
      Output
      ------
      None