Legend not showing up in Matplotlib stacked area plot

Question

I am creating a stacked line/area plot using plt.fill_between() method of the pyplot, and after trying so many things I am still not able to figure why it is not displaying

Answer 1

gcalmettes's answer was a helpful start, but I wanted my legend to pick up the colors that the stackplot had automatically assigned. Here's how I did it:

polys = pyplot.stackplot(x, y)
legendProxies = []
for poly in polys:
    legendProxies.append(pyplot.Rectangle((0, 0), 1, 1, fc=poly.get_facecolor()[0]))