fn check_if_balanced(tokens: &[Token]) -> bool {
        let mut delims = 0;

        for token in tokens {
            match token {
                Token::Open(_) => delims += 1,
                Token::Close(_) => delims -= 1,
                _ => continue,
            };

            if delims < 0 {
                return false;
            }
        }

        delims == 0
    }
Checks if there are a matching number of opening and
closing delims. Doesn't care if delims are of
different types To be used with
`generate_minimal_source`.
passerine/src/compiler/read.rs