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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def daily_temperature_range(tasmax, tasmin, freq='YS'):
 r"""Mean of daily temperature range. The mean difference between the daily maximum temperature and the daily minimum temperature. 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 The average variation in daily 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 mean diurnal temperature range in period :math:`j` is: .. math:: DTR_j = \frac{ \sum_{i=1}^I (TX_{ij} - TN_{ij}) }{I} """


    dtr = tasmax - tasmin
    out = dtr.resample(time=freq).mean(dim='time', keep_attrs=True)
    out.attrs['units'] = tasmax.units
    return out