def _missing_fields(record):
    """
    Accepts a record from a csv.DictReader object and determines if any
    fields have been filled in with None by the DictReader. Returns a list of
    field names that have been filled in with None type, or false if all fields are
    present.
    """
    missing_fields = False
    for key in record:
        if record[key] is None:
            if not missing_fields:
                missing_fields = []
            missing_fields.append(key)
    return missing_fields
