pub fn render_h(n: u8, state: &mut State, stack: Vec<String>, args: Vec<String>) -> String {
    let environment_name = "heading".to_owned();
    let heading_state = if let Some(es) = state.get_environment_state::<GlobalHeadingState>(environment_name.clone()) {
        es
    } else {
        state.create_environment_state(environment_name, GlobalHeadingState::new());
        // Now we have an ensured state inside the states list and we can safely retrieve it.
        state.get_environment_state::<GlobalHeadingState>(environment_name).unwrap()
    };

    heading_state.specific[n as usize].current_number += 1;
    let current_number = heading_state.specific[n as usize].current_number;


    if stack.len() > 0 && stack[0] == "html" {
        format!("<h{0}>{1}</h{0}>", n, args.join(" "))
    } else {
        println!("No suitable environment known.");
        "".into()
    }
}