anchor.diff:              "price":120
               "currency":"CZK"
               "_order_id":1
  +            "payed":true
  +        },
  +        {
  +            "name":"kniha 1",
  +            "_id":1,
  +            "url":"/book/1",
  +            "price":120
  +            "currency":"CZK"
  +            "_order_id":1
  +            "payed":false
           }
       ],
       "favourite":[
  
positive.code: { "users": [
  {   "_id":1
      "url": "/users/1",
      "name":"pan", 
      "surname":"tam",
      "buyed": [
          {
  
negative.code:             "_order_id":1
          }
      ],
      "type":"registered"
  }
  ] }
  
  GET /user/:id
  < 200
  < Content-Type: application/json
  {   "_id":1
      "url": "/users/1",
      "name":"pan",
      "surname":"tam",
      "buyed": [
          {
              "name":"kniha 1",
              "_id":1,
              "url":"/book/1",
              "price":120
              "currency":"CZK"
              "_order_id":1
              "payed":true
          },
          {
              "name":"kniha 1",
              "_id":1,
              "url":"/book/1",
              "price":120
              "currency":"CZK"
              "_order_id":1
              "payed":false
          }
      ],
      "favourite":[
                  {
              "name":"kniha 1",
              "_id":1,
              "url":"/book/1",
              "price":120
              "currency":"CZK"
              "_order_id":1
          }
      ],
      "type":"registered"
  }
  
  Save new products in your shopping cart
  POST /shopping-cart
  