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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 heat_wave_index(tasmax, thresh='25.0 degC', window=5, freq='YS'):
 r"""Heat wave index. Number of days that are part of a heatwave, defined as five or more consecutive days over 25℃. Parameters tasmax : xarrray.DataArray Maximum daily temperature [℃] or [K] thresh : str Threshold temperature on which to designate a heatwave [℃] or [K]. Default: '25.0 degC'. window : int Minimum number of days with temperature above threshold to qualify as a heatwave. freq : str, optional Resampling frequency Returns ------- DataArray Heat wave index. """

    thresh = utils.convert_units_to(thresh, tasmax)
    over = tasmax > thresh
    group = over.resample(time=freq)

    return group.apply(rl.windowed_run_count, window=window, dim='time')