pub fn merge_option<T: Clone, F>( opt1: &Option<T>, opt2: &Option<T>, merge: F ) -> Option<T>where F: Fn(&T, &T) -> T,
Helper function to merge to values wrapped in Option<..>. Merges (Some(x), None) to Some(x).
Option<..>
(Some(x), None)
Some(x)