History of Mark::step 1 change

In crates/backdrop/src/mark.rs, lines 101–107 on dd0788b756f2d77e53606aef21f1927b97ebdfd6948b7c39d25e71950b77448d. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 101,107:crates/backdrop/src/mark.rs.