Function generate_integers 

pub fn generate_integers<N: Node, F: FnMut(&str) -> Result<(), Error>, G: FnMut(&str) -> Result<N, Error>, H: FnMut(&Url) -> Result<String, Error>>(
    ctxt: &Context<N>,
    stctxt: &mut StaticContext<N, F, G, H>,
    _start_at: &Transform<N>,
    select: &Transform<N>,
    num: &Numbering<N>,
) -> Result<Sequence<N>, Error>

Generate a sequence of integers