code: def get_threadline_theming(self, thread):
          
          colours = int(self._config.get('colourmode'))
          return self._theme.get_threadline_theming(thread, colours)
docs: looks up theming info a threadline displaying a given thread. This
          wraps around :meth:`~alot.settings.theme.Theme.get_threadline_theming`,
          filling in the current colour mode.
  
          :param thread: thread to theme
          :type thread: alot.db.thread.Thread