def page_double_hyphen(record):
    """
    Separate pages by a double hyphen (--).

    :param record: the record.
    :type record: dict
    :returns: dict -- the modified record.

    """
    if "pages" in record:
        if "-" in record["pages"]:
            p = [i.strip().strip('-') for i in record["pages"].split("-")]
            record["pages"] = p[0] + '--' + p[-1]
    return record