Macro doe::targets

macro_rules! targets {
    ($($key:expr => $value:expr),*) => { ... };
}

implment targets! for return Vec<(Box<dyn ToString>,Box<dyn ToString>)>

fn main() {
   use doe::Print;
   use doe::Str;
   "this is a {s},I like Trait Object {p}%"
   .format(vec![(Box::new("{s}"),Box::new("demo")),(Box::new("{p}"),Box::new(100))]).println();//this is a demo,I like Trait Object 100%
    use doe::targets;
    "this is a {d},I like Trait Object {p}}%"
    .format(targets!{"{d}"=>"demo","{p}"=>100})
    .println(); //this is a demo,I like Trait Object 100%
}