Function pageout 

pub fn pageout(chunks: &mut [Vec<u64>]) -> Handle

Available on crate feature pager and Unix only.

Scatter pageout. Logical layout = chunks concatenated in order. After return, each Vec in chunks is empty. File backend preserves capacity; swap backend moves the alloc into the handle. Empty input returns a len == 0 handle of the active backend’s variant (no I/O is performed in either backend).

Panics on I/O failure. Use try_pageout to surface the error.