dict containing sets?

struct CopyableSet[T: KeyElement](CollectionElement):  # we need this because set is not copyable :S
    var set: Set[T]

    fn __init__(inout self: Self):
        self.set = Set[T]()

    fn __copyinit__(inout self: Self, existing: Self):
        self.set = Set[T]()
        self.set._data = existing.set._data

    fn __moveinit__(inout self: Self, owned other: Self):
        self.set = other.set^

fn create_rag(indices: FlatTensor[DType.uint16]) -> Dict[Int, CopyableSet[Int]]:
    neighbor_offsets = List[List[Int]](
        List(1, 0), List(-1, 0), List(0, 1), List(0, -1)
    )
    rag = Dict[Int, CopyableSet[Int]]()
    max_label, _ = max[DType.uint16](indices, 0, len(indices.buffer))
    for label in range(1, max_label + 1):
        rag[label] = CopyableSet[Int]()

    for row in range(S):
        for col in range(S):
            current_label = indices.buffer[rowcol_to_ind(row, col)].__int__()
            if current_label == 0:
                print('tremendous mistake!')
               
            for i in range(len(neighbor_offsets)):
                nrow = row + neighbor_offsets[i][0]
                ncol = col + neighbor_offsets[i][1]
                if 0 <= nrow and nrow < S and 0 <= ncol and ncol < S:
                    neighbor_label = indices.buffer[rowcol_to_ind(nrow, ncol)]
                    if neighbor_label != current_label:
                        aux = rag[current_label]  # this line fails
                        aux.set.add(neighbor_label.__int__())
                        rag[current_label] = aux
    return rag