2 fn example_err(prog: &str, arg: &str) {
3 println!("{}: {}", prog, arg)
6 fn exit<F>(print: F, prog: &str, arg: &str) where F: FnOnce(&str, &str) {
10 struct X<F> where F: FnOnce(&str, &str) {
14 impl<F> X<F> where F: FnOnce(&str, &str) {
16 exit(self.err, "prog", "arg");