docs: def run_friedman82_basic():
      """Run Friedman's test of fixed-span smoothers from Figure 2b."""
      x, y = build_sample_smoother_problem_friedman82()
      plt.figure()
      # plt.plot(x, y, '.', label='Data')
      for span in smoother.DEFAULT_SPANS:
          smooth = smoother.BasicFixedSpanSmoother()
          smooth.specify_data_set(x, y, sort_data=True)
          smooth.set_span(span)
          smooth.compute()
          plt.plot(x, smooth.smooth_result, '.', label='span = {0}'.format(span))
      plt.legend(loc='upper left')
      plt.grid(color='0.7')
      plt.xlabel('x')
      plt.ylabel('y')
      plt.title('Demo of fixed-span smoothers from Friedman 82')
      plt.savefig('sample_friedman82.png')
  
      return smooth