r"""Frequency of extreme warm nights

    Return the number of days with tasmin > thresh per period

    Parameters
    ----------
    tasmin : xarray.DataArray
      Minimum daily temperature [℃] or [K]
    thresh : str
      Threshold temperature on which to base evaluation [℃] or [K]. Default : '22 degC'
    freq : str, optional
      Resampling frequency

    Returns
    -------
    xarray.DataArray
      The number of days with tasmin > thresh per period

def warm_night_frequency(tasmin, thresh='22 degC', freq='YS'):
    r"""Frequency of extreme warm nights

    Return the number of days with tasmin > thresh per period

    Parameters
    ----------
    tasmin : xarray.DataArray
      Minimum daily temperature [℃] or [K]
    thresh : str
      Threshold temperature on which to base evaluation [℃] or [K]. Default : '22 degC'
    freq : str, optional
      Resampling frequency

    Returns
    -------
    xarray.DataArray
      The number of days with tasmin > thresh per period
    """
    thresh = utils.convert_units_to(thresh, tasmin, )
    events = (tasmin > thresh) * 1
    return events.resample(time=freq).sum(dim='time')