     bucket_difference(bucket1, bucket2)
   end
 
-  defp bucket_difference([], bucket) do
+  defp bucket_difference([], _bucket) do
     { [], 0 }
   end
 

    case node_delete(root, depth, pos, member) do
      { _, value, 0 } ->
        { set, value, 0 }
      { root, value, -1 } ->
        { if depth > 0 and trie(set, :contract_on) == size do
          root = node_contract(root, depth)
          trie(set,

    bucket_get(bucket, candidate)
  end

  defp bucket_get(_, _member) do
    nil
  end

