Perform widget rendering, but do not print anything.

def _render_content(self, content, **settings):
        """
        Perform widget rendering, but do not print anything.
        """
        bar_len = int(settings[self.SETTING_BAR_WIDTH])
        if not bar_len:
            bar_len = TERMINAL_WIDTH - 10
        percent = content
        progress = ""
        progress += str(settings[self.SETTING_BAR_CHAR]) * int(bar_len * percent)
        s = {k: settings[k] for k in (self.SETTING_FLAG_PLAIN,)}
        s.update(settings[self.SETTING_BAR_FORMATING])
        progress = self.fmt_text(progress, **s)
        progress += ' ' * int(bar_len - int(bar_len * percent))
        return "{:6.2f}% [{:s}]".format(percent * 100, progress)