use std::borrow::Cow;

fn remove_spaces<'a, T: 'a + AsRef<str>>(input: & 'a T) -> Cow<'a, str> {
    if input.as_ref().contains(' ') {
        let mut buf = String::with_capacity(input.as_ref().len());
        for c in input.as_ref().chars() {
            if c!= ' ' {
                buf.push(c);
            }
        }
        return Cow::Owned(buf);
    }
    return Cow::Borrowed(input.as_ref());
}

fn main() {
    let x = "he llo,wor ld!".to_string();
    let ret = remove_spaces(&x);
    println!("{:?}", ret);
}