Pop quizz!
Do you think that in Rust, `c.is_ascii() && c.is_white_space()` => `c.is_ascii_whitespace()`?
Or put differently, is there an input for which this function will not panic (without using unsafe)?
```rust
fn foo(c: char) {
assert!(c.is_whitespace());
assert!(c.is_ascii());
// Mind the negation below
assert!(!c.is_ascii_whitespace());
}
```

