for statement in basic_block.statements.iter_mut() {
match statement.kind {
StatementKind::AscribeUserType(..)
+ | StatementKind::PlaceMention(..)
| StatementKind::Assign(box (_, Rvalue::Ref(_, BorrowKind::Shallow, _)))
| StatementKind::FakeRead(..) => statement.make_nop(),
_ => (),