s/^/ab\n/ s/.*/&&&&&&&&&&&&&&&/ s/$/acd\nacd\nacd\n/ s/$/efcd\n/ s/efcd./&&&&/ s/$/eghd\n/ s/$/egi\n/ s/egi./&&&&&&&&&/ s/[abe]/&&&&&&&&&&&&&&/g;s/a[^a]/aaaa&/g;s/[^b]b/&b/g s/[cdgi]/&&&&&&&/g;s/g[^g]/ggg&/g;s/[^i]i/&ii/g;s/[^d]d/&d/g s/f/&&&&/g s/./ &/gm
Note that non-ascii characters in the above source code will be escaped (such as \x9f).