Function croaring_sys_mw::roaring_bitmap_select

pub unsafe extern "C" fn roaring_bitmap_select(
    ra: *const roaring_bitmap_t, 
    rank: u32, 
    element: *mut u32
) -> bool

If the size of the roaring bitmap is strictly greater than rank, then this function returns true and set element to the element of given rank. Otherwise, it returns false.