hacer un left join en sequelize code example

Example: left join in sequelize

Shop.findAll({
     where:{id:shopId}, 
     include:[
         { model:ShopAd, as:'ads', 
           where:{ 
                 is_valid:1, 
                 is_vertify:1},   
           required:false
           }
         ]
      })
      .success(function(result) {
        callback(result);
    });