Function stream_forward 

pub(crate) fn stream_forward(
    name: &str,
    stream_id: u32,
    label: &str,
    lines: &[String],
)

Forward a batch of complete lines from one stream to the matching standard stream of the scheduler, and abort when the kernel reports an error on a stderr stream. Lines prefixed “IGN: “ are dropped instead of forwarded, for prints with side effects that nobody needs to see, the arena association print in scx_arena_subprog_init() for example.