fn peek2(&self) -> Option<char> {
        let mut it = self.chars.clone();
        it.next()?;
        it.next()
    }
/// Peek the next next char.
Peek the next next char.
Peek the next next char .
fn peek2(&self) -> Option<char> {
        let mut it = self.chars.clone();
        it.next()?;
        it.next()
    }
fn peek2 ( & self ) -> Option < char > { let mut it = self . chars . clone ( ) ; it . next ( ) ? ; it . next ( ) }
Peek the next next char.
Peek the next next char .
&self
&self