code: def plot_color_legend(legend, horizontal=False, ax=None):
      
      import matplotlib.pyplot as plt
      import numpy as np
      t = np.array([np.array([x for x in legend])])
      if ax is None:
          fig, ax = plt.subplots(1, 1)
      if horizontal:
          ax.imshow(t, interpolation='none')
          ax.set_yticks([])
          ax.set_xticks(np.arange(0, legend.shape[0]))
          t = ax.set_xticklabels(legend.index)
      else:
          t = t.reshape([legend.shape[0], 1, 3])
          ax.imshow(t, interpolation='none')
          ax.set_xticks([])
          ax.set_yticks(np.arange(0, legend.shape[0]))
          t = ax.set_yticklabels(legend.index)
      return ax
docs: Plot a pandas Series with labels and colors.
  
      Parameters
      ----------
      legend : pandas.Series
          Pandas Series whose values are RGB triples and whose index contains
          categorical labels.
  
      horizontal : bool
          If True, plot horizontally.
  
      ax : matplotlib.axis
          Axis to plot on.
  
      Returns
      -------
      ax : matplotlib.axis
          Plot axis.