def compute_call_value(story_data):
    """
        Computes the value of a call based on duration, onnet/offnet and time
        of the day.

        This is meant to be called in an Apply of the CDR use case
    """
    price_per_second = 2

    # no, I'm lying, we just look at duration, but that's the idea...
    df = story_data[["DURATION"]] * price_per_second

    # must return a dataframe with a single column named "result"
    return df.rename(columns={"DURATION": "result"})