From `strace` examinations, far fewer `splice()/send_file()` are used from the consumer of a `collect` in the middle of a pipe.
A reduction of over 5 times. But still not just a single one.

# TODO: single syscall reads from consumers of `collect` in pipelines
Is there a way we can set the size of `stdout` before exiting?
I dunno what `sealing` is, but maybe that can be used? Or, if not, a specific `fcntl()` call? Finding this out will allow consumers of `collect`'s output to use a single `splice()` instead of many, greatly improving its performance in pipelines as its output can be used like an actual file's...