History of Pool::keep 3 changes

In crates/flow/src/cache.rs, lines 231–265 on eb8e445f27b6654850d7e4819994dc2cc8510985f4f3052201cbb87c382cd14e. 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 231,265:crates/flow/src/cache.rs.