fix stream code style

[yjhmelody]

I think the pub $vis in stream also are style inconsisitent.
Because like new fn is only used by super module, pub(crate) / pub(super) / pub are all no different.

[yjhmelody]

@taiki-e why use pub(crate) rather than pub(super)?

[yoshuawuyts]

Looks like a nice bit of cleanup. Thanks heaps!