I wanted to see how different the code would be if we used strings for the ca_lines instead of lists. The string version is a bit shorter and simpler. Interestingly, set_display_from_lines, the method that uses two zips, is almost identical. Virtually the only difference is that the left and right padding consist of strings of "0"s rather than lists of 0's.

The string version is ca_outline_strings in GitHub. You may use either version.