/// Function to handle errors in a way that prints a message and exits the program.
/// result.unwrap_or_else(handle_error("An error occurred"))
/// Prints "An error occurred: <error message>" and exits on error.
pubfnhandle_error<T, E:std::fmt::Display>(msg:&'staticstr)-> impl FnOnce(E)-> T{move|e|{eprintln!("{}: {}", msg, e);std::process::exit(1);}}