code: def _render_border_line(self, t, settings):
          
          s = self._es(settings, self.SETTING_WIDTH, self.SETTING_MARGIN, self.SETTING_MARGIN_LEFT, self.SETTING_MARGIN_RIGHT)
          w = self.calculate_width_widget(**s)
          s = self._es(settings, self.SETTING_BORDER_STYLE, self.SETTING_BORDER_FORMATING)
          border_line = self.fmt_border(w, t, **s)
          s = self._es(settings, self.SETTING_MARGIN, self.SETTING_MARGIN_LEFT, self.SETTING_MARGIN_RIGHT, self.SETTING_MARGIN_CHAR)
          border_line = self.fmt_margin(border_line, **s)
          return border_line
docs: Render box border line.