Serialize break element.

def serialize_break(ctx, document, elem, root):
    "Serialize break element."

    if elem.break_type == u'textWrapping':
        _div = etree.SubElement(root, 'br')
    else:
        _div = etree.SubElement(root, 'span')
        if ctx.options['embed_styles']:
            _div.set('style', 'page-break-after: always;')

    fire_hooks(ctx, document, elem, _div, ctx.get_hook('page_break'))

    return root