Function process 

pub fn process<T, I, P, F, R>(
    init: I,
    process_data: P,
    finalize: F,
    render: R,
) -> Result<(), Box<dyn Error>>
where
    I: FnOnce() -> Result<T, Box<dyn Error>>,
    P: FnOnce(T) -> Result<T, Box<dyn Error>>,
    F: FnOnce(T) -> Result<Context, Box<dyn Error>>,
    R: FnOnce(Context) -> Result<Context, Box<dyn Error>>,