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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 tg10p(tas, t10, freq='YS'):
 r"""Number of days with daily mean temperature below the 10th percentile. Number of days with daily mean temperature below the 10th percentile. Parameters tas : xarray.DataArray Mean daily temperature [℃] or [K] t10 : xarray.DataArray 10th percentile of daily mean temperature [℃] or [K] freq : str, optional Resampling frequency Returns ------- xarray.DataArray Count of days with daily mean temperature below the 10th percentile [days] Notes ----- The 10th percentile should be computed for a 5 day window centered on each calendar day for a reference period. Example ------- """

    if 'dayofyear' not in t10.coords.keys():
        raise AttributeError("t10 should have dayofyear coordinates.")

    t10 = utils.convert_units_to(t10, tas)

    # adjustment of t10 to tas doy range
    t10 = utils.adjust_doy_calendar(t10, tas)

    # create array of percentile with tas shape and coords
    thresh = xr.full_like(tas, np.nan)
    doy = thresh.time.dt.dayofyear.values
    thresh.data = t10.sel(dayofyear=doy)

    # compute the cold days
    below = (tas < thresh)

    return below.resample(time=freq).sum(dim='time')