Function join_input_map 

pub fn join_input_map<T>(
    map: &[Option<T>],
    next_map: &[Option<T>],
) -> Vec<Option<T>>
where
    T: Clone + Copy,
    usize: TryFrom<T>,
    <usize as TryFrom<T>>::Error: Debug,

Joins input/output maps from previous and next operation and returns joined input/output map.

A map is first input map and next_map is second map.