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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_xmlid(ctx, record, xmlid, noupdate=False):
 """ Add a XMLID on an existing record """

    try:
        ref_id, __, __ = ctx.env['ir.model.data'].xmlid_lookup(xmlid)
    except ValueError:
        pass  # does not exist, we'll create a new one
    else:
        return ctx.env['ir.model.data'].browse(ref_id)
    if '.' in xmlid:
        module, name = xmlid.split('.')
    else:
        module = ''
        name = xmlid
    return ctx.env['ir.model.data'].create({
        'name': name,
        'module': module,
        'model': record._name,
        'res_id': record.id,
        'noupdate': noupdate,
    })