code: public void indent() throws IOException {
          for (int i=0; i<indent; i++) writeRawString("   ");
      }
  
      /**
       * Method to increase the indent depth of the output writer.
       * @throws IOException Thrown if an error occurs during write.
       */
      public void indentPush()
      {
          indent++;
      }
  
      /**
       * Method to reduce the indent depth of the output writer.
       */
      public void indentPop()
      {
          indent--;
          if (indent < 0) throw new IllegalStateException();
      }
  
      /**
       * Method to get a list of all the property names stored in a map.
       */
      public List getPropertyNames(Map map)
      {
          List propertyNames = super.getPropertyNames(map);
  
          Collections.sort(propertyNames);
  
          return propertyNames;
      }
  
  }
docs: Method to write an indent to the output writer.
  @throws IOException Thrown if an error occurs during write.