Macro parallel 

macro_rules! parallel {
    ( $( $op:expr ),* $(,)? ) => { ... };
}

Execute Animations at once.

            parallel![
                cw.add_lines()
                    .str(
                        r"
fn fib(n: u32) -> u32 {
    match n {
        0 => 0,
        1 => 1,
        _ => fib(n - 1) + fib(n - 2),
    }
}
                "
                    )
                    .over(5.s())
                    .style(CodeAnimationStyle::TypeWriterInstantResize),
                typing.play(),
            ],