def default_preprocessing(df):
    """Perform the same preprocessing as the original analysis:
    https://github.com/propublica/compas-analysis/blob/master/Compas%20Analysis.ipynb
    """
    return df[(df.days_b_screening_arrest <= 30)
            & (df.days_b_screening_arrest >= -30)
            & (df.is_recid != -1)
            & (df.c_charge_degree != 'O')
            & (df.score_text != 'N/A')]