No problem:

        category_count = new Hash();
        seen = new Hash();
        
        handle_article(path, category, article_body) {
            ...
            # lots of stuff
            ...
        
            # count number of articles in each category
            if ( not seen[path] ) {
              category_count[category]++
              seen[path] = True
            }
        }

It's a bloody miracle, that's what it is.