code: def pretty_polyfit_plot(x, y, deg=1, xlabel=None, ylabel=None, **kwargs):
      
      plt = pretty_plot(**kwargs)
      pp = np.polyfit(x, y, deg)
      xp = np.linspace(min(x), max(x), 200)
      plt.plot(xp, np.polyval(pp, xp), 'k--', x, y, 'o')
      if xlabel:
          plt.xlabel(xlabel)
      if ylabel:
          plt.ylabel(ylabel)
      return plt
docs: Convenience method to plot data with trend lines based on polynomial fit.
  
      Args:
          x: Sequence of x data.
          y: Sequence of y data.
          deg (int): Degree of polynomial. Defaults to 1.
          xlabel (str): Label for x-axis.
          ylabel (str): Label for y-axis.
          \\*\\*kwargs: Keyword args passed to pretty_plot.
  
      Returns:
          matplotlib.pyplot object.