docs: def color_electrodes(self, config_nr, ax):
          """
          Color the electrodes used in specific configuration.
          Voltage electrodes are yellow, Current electrodes are red ?!
          """
          electrodes = np.loadtxt(options.config_file, skiprows=1)
          electrodes = self.configs[~np.isnan(self.configs).any(1)]
          electrodes = electrodes.astype(int)
  
          conf = []
          for dim in range(0, electrodes.shape[1]):
              c = electrodes[config_nr, dim]
              # c = c.partition('0')
              a = np.round(c / 10000) - 1
              b = np.mod(c, 10000) - 1
              conf.append(a)
              conf.append(b)
          Ex, Ez = elem.get_electrodes()
          color = ['#ffed00', '#ffed00', '#ff0000', '#ff0000']
          ax.scatter(Ex[conf], Ez[conf], c=color, marker='s', s=60,
                     clip_on=False, edgecolors='k')