Macro clone 

macro_rules! clone {
    ($($x:ident),+ => $y:expr) => { ... };
}

Used as a shorthand syntax for calling .clone() when parsing variables into functions. Due to 'static requirements of many of the web apis move and clone are frequently required.

clone!(clone_item_1, clone_item_2, clone_item_3 => { expression using the clones })

Where the clone_item_x shadow existing variable names. So instead of writing:

let text = Mutable::new("text");
let other_text = Mutable::new("other text");
html!("div", {
    .event({
        let text = text.clone();
        let other_text = text.clone();
        move |_: events::Click| {
        text.set("clicked");
        other_text.set("clicked")
    }})
    .event({
        let other_text = other_text.clone();
        move |_: events::Focus| {
        text.set("focused");
        other_text.set("focused")
    }})
    .text_signal(other_text.signal_cloned())
});

clone! can make a cleaner syntax sharing the same variable names:

let text = Mutable::new("text");
let other_text = Mutable::new("other text");
html!("div", {
    .event(clone!(text, other_text => move |_: events::Click| {
        text.set("clicked");
        other_text.set("clicked")
    }))
    .event(clone!(other_text => move |_: events::Focus| {
        text.set("focused");
        other_text.set("focused")
    }))
    .text_signal(other_text.signal_cloned())
});