code: def draw_strip_text(self, text_lines, location, pid):
          
          ax = self.axs[pid]
          themeable = self.figure._themeable
          dim = self.strip_dimensions(text_lines, location, pid)
  
          if location == 'right':
              rotation = -90
              label = '\n'.join(reversed(text_lines))
          else:
              rotation = 0
              label = '\n'.join(text_lines)
  
          rect = mpatch.FancyBboxPatch((dim.box_x, dim.box_y),
                                       width=dim.box_width,
                                       height=dim.box_height,
                                       facecolor='lightgrey',
                                       edgecolor='None',
                                       transform=ax.transAxes,
                                       zorder=2.2,  # > ax line & boundary
                                       boxstyle='square, pad=0',
                                       clip_on=False)
  
          text = mtext.Text(dim.x, dim.y, label,
                            rotation=rotation,
                            verticalalignment='center',
                            horizontalalignment='center',
                            transform=ax.transAxes,
                            zorder=3.3,  # > rect
                            clip_on=False)
  
          ax.add_artist(rect)
          ax.add_artist(text)
  
          for key in ('strip_text_x', 'strip_text_y',
                      'strip_background_x', 'strip_background_y'):
              if key not in themeable:
                  themeable[key] = []
  
          if location == 'right':
              themeable['strip_background_y'].append(rect)
              themeable['strip_text_y'].append(text)
          else:
              themeable['strip_background_x'].append(rect)
              themeable['strip_text_x'].append(text)
docs: Create a background patch and put a label on it