code: def tx_min(tasmax, freq='YS'):
      r
  
      return tasmax.resample(time=freq).min(dim='time', keep_attrs=True)
docs: r"""Lowest max temperature
  
      The minimum of daily maximum temperature.
  
      Parameters
      ----------
      tasmax : xarray.DataArray
        Maximum daily temperature [℃] or [K]
      freq : str, optional
        Resampling frequency
  
      Returns
      -------
      xarray.DataArray
        Minimum of daily maximum temperature.
  
      Notes
      -----
      Let :math:`TX_{ij}` be the maximum temperature at day :math:`i` of period :math:`j`. Then the minimum
      daily maximum temperature for period :math:`j` is:
  
      .. math::
  
          TXn_j = min(TX_{ij})