python - Matplotlib transparent line plots

Question

I am plotting two similar trajectories in matplotlib and I'd like to plot each of the lines with partial transparency so that the red (plotted second) doesn't obscure the blue.

EDIT: Here's the image with transparent lines.

Answer 1

Plain and simple:

plt.plot(x, y, 'r-', alpha=0.7)

(I know I add nothing new, but the straightforward answer should be visible).