fn consume_punct(&mut self, expect: Punct) -> Result<bool, ParseErr> {
        match self.peek()?.kind {
            TokenKind::Punct(punct) if punct == expect => {
                self.get()?;
                Ok(true)
            }
            _ => Ok(false),
        }
    }
If the next token is an expected kind of Punctuator, get it and return true.
Otherwise, return false.
ruruby-parse/src/parser.rs