def column_rename(universe_dict):
    """Appends the name of the instrument to the columns.
    To help keep track of the instruments in the full dataset.

    :param universe_dict:               The dictionary of time series
    :type  universe_dict:               dict

    :return:                            The dictionary of time series
    :rtype:                             dict
    """
    for df_name in universe_dict:
        for col in universe_dict[df_name].columns:
            universe_dict[df_name].rename(columns={col: col + '_' + df_name
                }, inplace=True)
    return universe_dict
