History of Mark::step 1 change

In crates/backdrop/src/mark.rs, lines 101–107 on acb8d109e981553b233a60ad4df83f8f868e9ecb88214c56cd927d7f4944a1a4. 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.