Function find_subsequence 

pub fn find_subsequence<T>(haystack: &[T], needle: &[T]) -> Option<usize>
where
    for<'a> &'a [T]: PartialEq,

Convenience to see if a smaller byte sequence is in the larger sequence https://stackoverflow.com/questions/35901547/how-can-i-find-a-subsequence-in-a-u8-slice