code: public static int getAStoreReg(final DismantleBytecode dbc, final int seen) {
          if (seen == Const.ASTORE) {
              return dbc.getRegisterOperand();
          }
          if (OpcodeUtils.isAStore(seen)) {
              return seen - Const.ASTORE_0;
          }
  
          return -1;
      }
docs: returns the register used to store a reference
  
  @param dbc
  the dismantle byte code parsing the class
  @param seen
  the opcode of the store
  @return the register stored into