def deduplicate_list_of_periods(periods):
    """
    Deduplicates a list of ``Period`` objects, ensuring no two ``Period``s have
    the same id``
    """
    known_ids = []
    result = []

    for period in periods:
        if period.id not in known_ids:
            known_ids.append(period.id)
            result.append(period)

    return result