fn candidate_assign<'tcx, 'a>( stmts: &'a [(u128, &'a StatementKind<'tcx>)], otherwise: Option<&'a StatementKind<'tcx>>, ) -> Option<(Place<'tcx>, Vec<(u128, &'a Rvalue<'tcx>)>, Option<&'a Rvalue<'tcx>>)>