code: public Opcode getOpcode() {
          int b = getUnsignedByte(0);
          switch (b) {
              case Opcode.NONPRIV:
              case Opcode.PRIV:
              case Opcode.WIDE:
                  return Opcode.get(b, getUnsignedByte(1));
          }
          return Opcode.get(b);
      }
docs: Get the Opcode for this instruction, or null if the instruction is
  unrecognized.