Function read_at_many 

pub fn read_at_many(
    handle: &Handle,
    ranges: &[(usize, usize)],
    dst: &mut Vec<u64>,
)

Available on crate feature pager and Unix only.

Reads multiple ranges. Output appended to dst in request order (concat).

Ranges must be pairwise non-overlapping; ordering is otherwise unconstrained. Panics if any range is out of bounds, if two ranges overlap, or on I/O failure. Use try_read_at_many for fallible reads.