Plotting with a transparent marker but non-transparent edge

I'm trying to make a plot in matplotlib with transparent markers which have a fixed color edge . However, I can't seem to achieve a marker with transparent fill. I have a minimum working example here: ``` import numpy as np import matplotlib.pyplot as plt x = np.arange(10) y1 = 2*x + 1 y2 = 3*x - 5 plt.plot(x,y1, 'o-', lw=6, ms=14) plt.plot(x,y2, 'o', ms=14, markerfacecolor=None, alpha=0.5, markeredgecolor='red', markeredgewidth=5) plt.show() ``` I tried two techniques I found online to achieve this: 1) Setting alpha parameter. However, this makes the marker edge transparent too, which is not the desired effect. 2) Setting markerfacecolor=None, although this has no effect on my plot Is there a solution to this please?