def check_distinct_seasons(data):
    """A little helper function to check that seasons do not overlap -
    return true if the values are disticnt(valid) and do not
    overlap. returns false if the season are not distict and share
    some dates.
    """

    if len(data) <= 1:
        return True

    # pull out the dates, but only look a records with both start and end date
    dates = [
        (x.get("ssn_date0"), x.get("ssn_date1"))
        for x in data
        if x.get("ssn_date0") and x.get("ssn_date1")
    ]
    dates.sort()

    for i, x in enumerate(dates[:-1]):
        if x[1] >= dates[i + 1][0]:
            return False
    return True