gstuff
macro_rules! ERR { ($format: expr, $($args: tt)+) => { ... }; ($format: expr) => { ... }; }
Returns a Err(String), prepending the current location (file name and line number) to the string.
Err(String)
Examples: ERR! ("too bad"); ERR! ("{}", foo);
ERR! ("too bad")
ERR! ("{}", foo)