Macro tr 

macro_rules! tr {
    ($content:expr) => { ... };
    ($content:expr, $($arg:expr),+) => { ... };
    ([$prefix:expr] $content:expr) => { ... };
    ([$prefix:expr] $content:expr, $($arg:expr),+) => { ... };
}

Translate and content formatting.

Example

Assume that translate file are as follows:

{
    "Hello, {}": "Hello, {}",
    "birthday": {
        "Hello, {}": "Happy birthday, {}"
    }
}

[tr] will work like:

let name = "ho-229";
assert_eq!("Hello, ho-229", r18::tr!("Hello, {}", name));
assert_eq!("Hello, ho-229", r18::tr!([""] "Hello, {}", name));
assert_eq!("Happy birthday, ho-229", r18::tr!([".birthday"] "Hello, {}", name));