public void Start()
    {
        List <Character> roster = state.hr.GetRosterCharacters();

        for (int i = 0; i < roster.Count; ++i)
        {
            HeroRosterSlot slot = Instantiate <HeroRosterSlot>(slotPrefab, slotParent.transform);
            slot.Init(roster[i], this);
            slots.Add(roster[i], slot);
            UnitSelection selection = Instantiate <UnitSelection>(selectionPrefab, selectionParent.transform);
            Vector2       position  = start.anchoredPosition;
            position.x += i * 200;
            selection.SetPositionImmediate(position);
            selection.Init(roster[i], this);
            units.Add(roster[i], selection);
        }
    }