Problem

It would be nice if matplotlib's fill_between could fill the regions below two intersecting lines and above both lines. It can fill between both lines, but I haven't found a simple way to invert the region obtained previously. The only workarounds I have are to create some extra functions, or to swap foreground and background, both of which are cumbersome. There is a related issue with figures and code on stackoverflow: https://stackoverflow.com/questions/73447993/matplotlib-fill-between-invert

Proposed solution

Adding a boolean "invert" argument to fill_between would be nice