call the appropriate handler based on the first character in a token suspect
function tokenize() {

        var ch = walker.ch;
    
        if (ch === " " || ch === "\t") {
            return white();
        }

        if (ch === '/') {
            return comment();
        } 

        if (ch === '"' || ch === "'") {
            return str();
        }
        
        if (ch === '(') {
            return brace();
        }
    
        if (ch === '-' || ch === '.' || isDigit(ch)) { // tricky - char: minus (-1px) or dash (-moz-stuff)
            return num();
        }
    
        if (isNameChar(ch)) {
            return identifier();
        }

        if (isOp(ch)) {
            return op();
        }
        
        if (ch === "\n") {
            tokener("line");
            walker.nextChar();
            return;
        }
        
        throw error("Unrecognized character");
    }