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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 prep_for_graph(data_frame, series=None, delta_series=None, smoothing=None, outlier_stddev=None):
 """Prepare a dataframe for graphing by calculating deltas for series that need them, resampling, and removing outliers. """

    series = series or []
    delta_series = delta_series or []
    graph = calc_deltas(data_frame, delta_series)

    for s in series + delta_series:
        if smoothing:
            graph[s] = graph[s].resample(smoothing)
        if outlier_stddev:
            graph[s] = remove_outliers(graph[s], outlier_stddev)

    return graph[series + delta_series]