code: private static String getRegisterName(final Code obj, final int reg) {
          LocalVariableTable lvt = obj.getLocalVariableTable();
          if (lvt != null) {
              LocalVariable lv = lvt.getLocalVariable(reg, 0);
              if (lv != null) {
                  return lv.getName();
              }
          }
          return String.valueOf(reg);
      }
docs: returns the variable name of the specified register slot
  
  @param obj
  the currently parsed code object
  @param reg
  the variable register of interest
  
  @return the variable name of the specified register