def _add_dssp_ss_reduced(data):
    """
    Utility that adds a new column to the table.
    Adds a reduced-stated Secondary Structure (SS).

    :param data: pandas DataFrame object
    :return: returns a modified pandas DataFrame
    """
    table = data
    alphas = ['H']
    betas = ['E']
    coils = ['G', 'I', 'B', 'C', 'T', 'S', '', ' ']
    sss = []
    for ix in table.index:
        ss = table.loc[ix, 'SS']
        if ss in alphas:
            ss = 'H'
        elif ss in betas:
            ss = 'E'
        elif ss in coils:
            ss = 'C'
        else:
            ss = '-'
        sss.append(ss)
    table['SS_CLASS'] = sss
    return table
