def add_metadata(data):
    """
        Decorates a set of data (as produced by `normalised_sheet`)
        with metadata. At this time, this only wraps the results in
        a `data` key
    """

    # In the future this could add additional top-level fields like
    # date-created, original data source, alerts, and so on.

    return {
        "data": data
    }