We aim to solve a Knapsack problem where a set of items is given. 
For each item, we define a binary decision variable to indicate whether the item is included in the knapsack. 
The objective is to maximize the total utility of the selected items without exceeding a given weight limit.

Example input data:
1. items.csv
item_id,weight,utility
1,2,2
2,3,3
3,7,1
4,4,2
5,1,3

2. weight.csv
weight_limit
10