Macro qr_code 

macro_rules! qr_code {
    ($secret: expr, $name: expr, $title: expr, $width: expr, $height: expr, $level: expr) => { ... };
    ($secret: expr, $name: expr, $title: expr) => { ... };
}

A macro that can be used for convenient access to the function GoogleAuthenticator::qr_code, by providing a default of 200 to the width parameter, 200 to the height parameter, and ErrorCorrectionLevel::Medium to the level parameter.