code: def plot_kde(data, ax, title=None, color='r', fill_bt=True):
      
      if isinstance(data, list):
          data = np.asarray(data)
      e = kde.KDEUnivariate(data.astype(np.float))
      e.fit()
      ax.plot(e.support, e.density, color=color, alpha=0.9, linewidth=2.25)
      if fill_bt:
          ax.fill_between(e.support, e.density, alpha=.35, zorder=1,
                          antialiased=True, color=color)
      if title is not None:
          t = ax.set_title(title)
          t.set_y(1.05)
docs: Plot a smoothed (by kernel density estimate) histogram.
      :type data: numpy array
      :param data: An array containing the data to be plotted
  
      :type ax: matplotlib.Axes
      :param ax: The Axes object to draw to
  
      :type title: str
      :param title: The plot title
  
      :type color: str
      :param color: The color of the histogram line and fill. Note that the fill
                    will be plotted with an alpha of 0.35.
  
      :type fill_bt: bool
      :param fill_bt: Specify whether to fill the area beneath the histogram line