docs: async def send_webmention(self, entry, url):
          """ send a webmention from an entry to a URL """
  
          if (entry.url, url) in self._processed_mentions:
              LOGGER.debug(
                  "Skipping already processed mention %s -> %s", entry.url, url)
          self._processed_mentions.add((entry.url, url))
  
          LOGGER.debug("++WAIT: webmentions.get_target %s", url)
          target = await webmentions.get_target(self, url)
          LOGGER.debug("++DONE: webmentions.get_target %s", url)
  
          if target:
              LOGGER.debug("++WAIT: Sending webmention %s -> %s", entry.url, url)
              await target.send(self, entry)
              LOGGER.debug("++DONE: Sending webmention %s -> %s", entry.url, url)