title: Do I need to put the list back into treemap after adding to it
body: <p>Imagine I have a TreeMap&lt;Integer, List&gt; and then I call get(x) out of the TreeMap to get an existing list in the treemap and then with that list I then .add a new item into the list do I then need to put that list back into the treemap or is it automatically now in there so when I call 'get' on the treemap next that new item will also be in that list already without having called put to put it back in?</p>
  <p>Hopefully that makes sense lol, any confirmation is appreciated!</p>