What does this Cow example print, and how many heap allocations of the string data occur in process()?

use std::borrow::Cow; fn process(input: &str) -> Cow<str> { if input.contains(' ') { Cow::Owned(input.replace(' ', "_")) } else { Cow::Borrowed(input) } } fn main() { let a = process("no_spaces"); let b = process("has a space"); println!("{} {}", a, b); }