Write a function that takes a list of lists of integers and returns a single list containing all unique elements.

Ensure that the resulting list contains only unique elements.

For example, given the input [[1, 2, 3], [3, 4, 5], [5, 6]], the function should return [1, 2, 3, 4, 5, 6].

Complete the code of the solution function.

1. Fill in the code.
2. You can copy the code into IntelliJ/Android Studio, but it shouldn’t be necessary.
3. Click “run” – the green triangle. The code will compile and several tests will be run.
4. In the logs, you will see “try again” if the solution is incorrect, or “success” and a special code.
5. Provide this code in the form below along with your email and click “send”.
6. Solutions will be presented the next day on Instagram