pub fn reverse(number: i32) -> i32 {
  number
    // Convert to an absolute number without wrapping or panicking.
    .unsigned_abs()
    // Convert the number to string, then reverse all its characters.
    .to_string()
    .chars()
    .rev()
    // Collect the reversed characters back into a string.
    .collect::<String>()
    // Parse the string into an i32.
    .parse()
    // If it returns an Err then use 0 instead.
    .unwrap_or(0)
    // Then multiply by 0, 1 or -1 depending on the sign of the original number.
    * number.signum()
}

#[test]
fn test_reverse_integer() {
  assert_eq!(reverse(123), 321);
  assert_eq!(reverse(-123), -321);
  assert_eq!(reverse(120), 21);
  assert_eq!(reverse(i32::MAX), 0);
  assert_eq!(reverse(i32::MIN), 0);
}