code: def list_backups(self, encrypted=None, compressed=None, content_type=None,
                       database=None, servername=None):
          
          if content_type not in ('db', 'media', None):
              msg = "Bad content_type %s, must be 'db', 'media', or None" % (
                  content_type)
              raise TypeError(msg)
          # TODO: Make better filter for include only backups
          files = [f for f in self.list_directory() if utils.filename_to_datestring(f)]
          if encrypted is not None:
              files = [f for f in files if ('.gpg' in f) == encrypted]
          if compressed is not None:
              files = [f for f in files if ('.gz' in f) == compressed]
          if content_type == 'media':
              files = [f for f in files if '.tar' in f]
          elif content_type == 'db':
              files = [f for f in files if '.tar' not in f]
          if database:
              files = [f for f in files if database in f]
          if servername:
              files = [f for f in files if servername in f]
          return files
docs: List stored files except given filter. If filter is None, it won't be
          used. ``content_type`` must be ``'db'`` for database backups or
          ``'media'`` for media backups.
  
          :param encrypted: Filter by encrypted or not
          :type encrypted: ``bool`` or ``None``
  
          :param compressed: Filter by compressed or not
          :type compressed: ``bool`` or ``None``
  
          :param content_type: Filter by media or database backup, must be
                               ``'db'`` or ``'media'``
  
          :type content_type: ``str`` or ``None``
  
          :param database: Filter by source database's name
          :type: ``str`` or ``None``
  
          :param servername: Filter by source server's name
          :type: ``str`` or ``None``
  
          :returns: List of files
          :rtype: ``list`` of ``str``