code: def user_filter(config, message, fasnick=None, *args, **kw):
      
  
      fasnick = kw.get('fasnick', fasnick)
      if fasnick:
          return fasnick in fmn.rules.utils.msg2usernames(message, **config)
docs: A particular user
  
      Use this rule to include messages that are associated with a
      specific user.