use std::iter::FromIterator;
pub fn jumble(input_string: &str) -> String {
let mut letter_count = 0i32;
let mut result = "".to_owned();
for c in input_string.chars() {
match c {
'a'...'z' | 'A'...'Z' => {
match letter_count % 2 {
0 => result.push_str(&String::from_iter(c.to_uppercase())),
_ => result.push_str(&String::from_iter(c.to_lowercase()))
}
letter_count += 1
}
_ => result.push(c)
};
};
result
}