code: def return_dat(self, chan, begsam, endsam):
          
          return self.baseformat.dataset.return_dat(chan, begsam, endsam)
docs: Return the data as 2D numpy.ndarray.
  
          Parameters
          ----------
          chan : int or list
              index (indices) of the channels to read
          begsam : int
              index of the first sample
          endsam : int
              index of the last sample
  
          Returns
          -------
          numpy.ndarray
              A 2d matrix, with dimension chan X samples