code: def extreme_temperature_range(tasmax, tasmin, freq='YS'):
      r
  
      tx_max = tasmax.resample(time=freq).max(dim='time')
      tn_min = tasmin.resample(time=freq).min(dim='time')
  
      out = tx_max - tn_min
      out.attrs['units'] = tasmax.units
      return out
docs: r"""Extreme intra-period temperature range.
  
      The maximum of max temperature (TXx) minus the minimum of min temperature (TNn) for the given time period.
  
      Parameters
      ----------
      tasmax : xarray.DataArray
        Maximum daily temperature values [℃] or [K]
      tasmin : xarray.DataArray
        Minimum daily temperature values [℃] or [K]
      freq : str, optional
        Resampling frequency
  
      Returns
      -------
      xarray.DataArray
        Extreme intra-period temperature range for the given time period.
  
      Notes
      -----
      Let :math:`TX_{ij}` and :math:`TN_{ij}` be the daily maximum and minimum temperature at day :math:`i`
      of period :math:`j`. Then the extreme temperature range in period :math:`j` is:
  
      .. math::
  
          ETR_j = max(TX_{ij}) - min(TN_{ij})