FastSparseSet<Integer> (int key) { int index = 0; if (key < 0) { index = 2; key = -key; } else if (key >= VarExprent.STACK_BASE) { index = 1; key -= VarExprent.STACK_BASE; } FastSparseSet<Integer>[] arr = elements[index]; if (key < arr.length) { return arr[key]; } return null; }