docs: def add_custom_pin(plot, x, y, label, distance='3ex'):
      """Add a pin at the maximum value of a data series (sort of)"""
  
      # only use the second quarter, for cosmetic reasons
      q = int(0.25 * len(y))
      y = y[q:2*q]
      max_index = q + np.argmax(y)
      max_x = x[max_index]
      plot.add_pin(label, x=max_x, location='above', use_arrow=True,
                   style='pin distance=%s' % distance)