History of Mark::step 1 change

In crates/backdrop/src/mark.rs, lines 101–107 on d061ac87618c3b6171633725d2e7acf67af9c5cff5a70e860c88d1bde410fc74. 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.