example_item_data_list.json

[
    {
        "item_number":1,
        "mass":10,
        "delivery_time":1
    },
    {
        "item_number":2,
        "mass":20,
        "delivery_time":2
    },
    {
        "item_number":3,
        "mass":30,
        "delivery_time":3
    }
]