Method error

chapter24/src/main/java/com/seaofnodes/simple/Parser.java:2092–2092

(String msg)

        static final char SHL = 2, SAR = 3, SHR = 4;

        public char matchOperAssign() {
            skipWhiteSpace();
            if( match("<<=" ) ) return SHL;
            if( match(">>>=") ) return SHR;