def unitTransformed(unit,transform,freq):
    """
    :param unit: a data series' unit type
    :param transform: what transformation was applied to the data series
    :param freq: the frequency of the data series
    :return: returns a string representing unit transformed
    """
    if unit == "Index":
        unit_transformed = "Index"

    elif transform == "chg":
        if "%" in unit:
            unit_transformed = "Ppt. change"
        else:
            unit_transformed = "Level change"

    elif "pch" == transform and freq == "m":
        unit_transformed = "MoM %"
    elif "pca" == transform and freq == "q":
        unit_transformed = "QoQ AR %"
    else:
        unit_transformed = unit + " [{}]".format(transform)

    return unit_transformed