History of Mark::step 1 change

In crates/backdrop/src/mark.rs, lines 101–107 on a10446c68043dc8ad22b68048df2a70c0cc9adb8db19a064131933c5de7c4722. 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.