let a = [0, 1, 2, 3];

assert_eq!(a.iter().by_ref().copied().find_or_first(|e| *e == 5   ), Some(0)); // predicate is never satisfied, so `find_or_first` returns the first item (`0`)
assert_eq!(a.iter().by_ref().copied().find_or_nth(  |e| *e == 5, 1), Some(1)); // predicate is never satisfied, so `find_or_nth` returns the 2nd item (`1`) (count begins from `0`)
assert_eq!(a.iter().by_ref().copied().find_or_last( |e| *e == 5   ), Some(3)); // predicate is never satisfied, so `find_or_last` returns the last item (`3`)