old_contents: from been.core import DirectorySource, source_registry
  
  class Markdown(DirectorySource):
      kind = 'markdown'
      def process_event(self, event):
          lines = event['content'].splitlines()
          event['title'] = lines[0]
          event['content'] = "\n".join(lines[1:])
          event['summary'] = event['content']
          return event
  source_registry.add(Markdown)
  
new_contents: from been.core import DirectorySource, source_registry
  
  class MarkdownDirectory(DirectorySource):
      kind = 'markdown'
      def process_event(self, event):
          lines = event['content'].splitlines()
          event['title'] = lines[0]
          event['content'] = "\n".join(lines[1:])
          event['summary'] = event['content']
          return event
  source_registry.add(MarkdownDirectory)
  
subject: Rename Markdown source to MarkdownDirectory.