docs: public void add(int theOpCode) {
          if (opcodeCount(theOpCode) != 0)
              throw new IllegalArgumentException("Unexpected operands");
          int newStack = itsStackTop + stackChange(theOpCode);
          if (newStack < 0 || Short.MAX_VALUE < newStack)
              badStack(newStack);
          if (DEBUGCODE)
              System.out.println("Add " + bytecodeStr(theOpCode));
          addToCodeBuffer(theOpCode);
          itsStackTop = (short) newStack;
          if (newStack > itsMaxStack)
              itsMaxStack = (short) newStack;
          if (DEBUGSTACK) {
              System.out.println("After " + bytecodeStr(theOpCode)
                  + " stack = " + itsStackTop);
          }
          if (theOpCode == ByteCode.ATHROW) {
              addSuperBlockStart(itsCodeBufferTop);
          }
      }