 
   ## Bucket helpers
 
-  defp filter_bucket([e|bucket], fun) do
+  defp bucket_filter([e|bucket], fun) do
     case fun.(e) do
       true  ->
-        { new, count } = filter_bucket(bucket, fun)
+        { new, count } = bucket_filter(bucket, fun)
         { [e | new], count }
       false ->
-        { new, count } = filter_bucket(bucket, fun)
+        { new, count } = bucket_filter(bucket, fun)
         { new, count + 1 }
     end
   end
 
-  defp filter_bucket([], fun) do
+  defp bucket_filter([], fun) do
     {[], 0}
   end
 

  end

  defp node_filter(bucket, -1, fun, _) do
    filter_bucket(bucket, fun)
  end

  defp node_filter(node, depth, fun, count) when count >= 1 do

  end

  defp set_filter(ordered(bucket: bucket, size: size) = set, fun) do
    {new, removed_count} = bucket_filter(bucket, fun)
    ordered(bucket: new, size: size - removed_count)
  end

