function tokenize(line, callback)
        {
            var stream = new CodeMirror.StringStream(line);
            while (!stream.eol()) {
                var style = mode.token(stream, state);
                var value = stream.current();
                callback(value, style, stream.start, stream.start + value.length);
                stream.start = stream.pos;
            }
        }
@param {string} mimeType
@return {function(string, function(string, ?string, number, number))}