Remove <mods:relatedItem> tag in case that there is only <mods:location>
    subtag.

def fix_related_item_tag(dom):
    """
    Remove <mods:relatedItem> tag in case that there is only <mods:location>
    subtag.
    """
    location = dom.match(
        "mods:mods",
        "mods:relatedItem",
        "mods:location"
    )

    if not location:
        return
    location = first(location)

    location.replaceWith(
        dhtmlparser.HTMLElement()
    )

    # remove whole <mods:relatedItem> tag, if there is nothing else left in it
    related_item = dom.match(
        "mods:mods",
        "mods:relatedItem"
    )
    related_item = first(related_item)

    if not related_item.getContent().strip():
        related_item.replaceWith(dhtmlparser.HTMLElement())