Macro nes::err

macro_rules! err {
    ( $error:path ) => { ... };
    ( $error:path, $( $arg:expr ),* ) => { ... };
}

This macro generates error that gets information, where the error has been occurred. You should return it.

# Example

let file_name=match args.next() {
    Some( file_name ) => file_name,
    None => return err!(CommonError::NoArguments),
};

if !file_name.ends_with(".rs") {
    return err!(CommonError::IncorrectExtension, file_name, ".rs".to_string())
}