Function galil_seiferas::gs_find_by

pub fn gs_find_by<T, F>(text: &[T], pattern: &[T], equal: F) -> Option<usize> where
    F: Fn(&T, &T) -> bool, 

This is the Galil-Seiferas string matching algorithm.

If a match exists where pattern is a substring of text, return the offset to the start of the match inside Some(_). If not, return None.

Use equal as the equality comparison function.