Python code now often is limited either to 80 columns, or to 88 columns.
fci-mode allows drawing a vertical rule at a single column, but not two.
I'd like to do something very similar in appearance to
fci-mode, but draw two vertical lines instead of one. The line positions don't need to depend on the value of
fill-column: they should just always be columns 79 and 87. I want to show two lines only for python mode. How can I do that?