Macro verify_code 

macro_rules! verify_code {
    ($secret: expr, $code: expr, $discrepancy: expr, $time_slice: expr) => { ... };
    ($secret: expr, $code: expr) => { ... };
}

A macro that can be used for convenient access to the function GoogleAuthenticator::verify_code, by providing a default of 0 to the discrepancy parameter, and the current time to the times_slice parameter.