code: def thr_img(img, thr=2., mode='+'):
      
  
      vol  = read_img(img).get_data()
  
      if mode == '+':
          mask = vol > thr
      elif mode == '+-' or mode == '-+':
          mask = np.abs(vol) > thr
      elif mode == '-':
          mask = vol < -thr
      else:
          raise ValueError("Expected `mode` to be one of ('+', '+-', '-+', '-'), "
                           "got {}.".format(mode))
  
      return vol * mask
docs: Use the given magic function name `func` to threshold with value `thr`
      the data of `img` and return a new nibabel.Nifti1Image.
      Parameters
      ----------
      img: img-like
  
      thr: float or int
          The threshold value.
  
      mode: str
          Choices: '+' for positive threshold,
                   '+-' for positive and negative threshold and
                   '-' for negative threshold.
      Returns
      -------
      thr_img: nibabel.Nifti1Image
          Thresholded image