optimize newIn
optimize newIn

benchmark             old ns/op     new ns/op     delta
BenchmarkInExpr-4     6134          4041          -34.12%

benchmark             old allocs     new allocs     delta
BenchmarkInExpr-4     10             8              -20.00%

benchmark             old bytes     new bytes     delta
BenchmarkInExpr-4     288           224           -22.22%

oov/q