I've got an array of objects like this:

```
[
  { week: 1, day: 1, todo: "eq1" },
  { week: 1, day: 3, todo: "eq2" },
  { week: 4, day: 6, todo: "eq3" },
  { week: 4, day: 7, todo: "eq4" },
]

```

I would like to transform to sth like this:

```
[ 
   1: {
       1: { todo: "eq1" },
       3: { todo: "eq2" }
   },
   4: {
       6: { todo: "eq3" },
       7: { todo: "eq4" }
   }
]

```

How can I do it?