text: describe("groupById", function() {
  
    it("creates an object grouped by id", function() {
      let users = [
        {id: 'john', name: "John Smith", age: 20},
        {id: 'ann', name: "Ann Smith", age: 24},
        {id: 'pete', name: "Pete Peterson", age: 31},
      ];
  
      assert.deepEqual(groupById(users), {
        john: {id: 'john', name: "John Smith", age: 20},
        ann: {id: 'ann', name: "Ann Smith", age: 24},
        pete: {id: 'pete', name: "Pete Peterson", age: 31},
      });
    });
  
    it("works with an empty array", function() {
      users = [];
      assert.deepEqual(groupById(users), {});
    });
  });
  