Function or6 

pub fn or6<A, B, C, D, E, F, V>(
    a: A,
    b: B,
    c: C,
    d: D,
    e: E,
    f: F,
) -> impl Parser<Out = V>
where
    A: Parser<Out = V>,
    B: Parser<Out = V>,
    C: Parser<Out = V>,
    D: Parser<Out = V>,
    E: Parser<Out = V>,
    F: Parser<Out = V>,