That's more or less right, masklinn. To the above writers, look at the Python source (I can't vouch for how the C implementation does things). It's not beautifu

That's more or less right, masklinn. To the above writers, look at the Python source (I can't vouch for how the C implementation does things). It's not beautiful, but it's also not hard to understand. The effective work is all done inside a big function. To customize it, you'd have to split that function into pieces and then glue it back together using a class or your own function coordinating the parts.