def denormalize(reference, series, 
                normalized_variable='close_point_relative_normalization',
                denormalized_variable='close'):
    """
    Denormalizes the values for a given series.
    
    Parameters
    ----------
    reference: pd.DataFrame
        DataFrame to use as reference. This dataframe
        contains both a week index and the USD price
        reference that we are interested on.

    series: 

    normalized_variable: str

    denormalized_variable: str    
    
    Returns
    -------
    A modified DataFrame with the new variable provided
    in `denormalized_variable` parameter.
    """
    week_values = reference[
        reference['iso_week'] == series['iso_week'].values[0]]
    last_value = week_values[denormalized_variable].values[0]
    series[denormalized_variable] = last_value * (series[normalized_variable] + 1)

    return series