docs: def scales(scale=None):
      """
      Displays a color scale (HTML)
  
      Parameters:
      -----------
              scale : str
                      Color scale name
                      If no scale name is provided then all scales are returned
                              (max number for each scale)
                      If scale='all' then all scale combinations available 
                              will be returned
  
      Example:
              scales('accent')
              scales('all')
              scales()
      """
      if scale:
          if scale == 'all':
              display(HTML(cl.to_html(_scales)))
          else:
              display(HTML(cl.to_html(get_scales(scale))))
      else:
          s = ''
          keys = list(_scales_names.keys())
          keys.sort()
          for k in keys:
              scale = get_scales(k)
              s += '<div style="display:inline-block;padding:10px;"><div>{0}</div>{1}</div>'.format(
                  k, cl.to_html(scale))
          display(HTML(s))