How do I fill in the space beneath curve "a" (the sloping up line) and above "b" (horizontal)? Thank you.
#Plot data
sns.set(font_scale = 1.5, style = 'white', rc=None)
fig, ax = plt.subplots(figsize = (15,10))
a = sensitivity.plot(y = 0.2, ax = ax, linestyle = '--', color = 'gray')
b = sensitivity.plot(y = 0.3, ax = ax, linestyle = '-.', color = 'gray')
c = sensitivity.plot(y = 0.4, ax = ax, linestyle = ':', color = 'gray')
d = ax.hlines(y=7.5, xmin=100, xmax=900, colors='black', linestyles='-', lw=2, label='Single Short Line')
Output: