Function wants_input 

pub fn wants_input(program: &str) -> bool

Checks if the program will try to read user input.

let reads = ",[>+>+<<-]>.>.";
let does_not_read = "foo. bar.";

assert_eq!(true, bf_lib::wants_input(reads));
assert_eq!(false, bf_lib::wants_input(does_not_read));