code: protected void pushAttrib(PdfDictionary dict) {
          PdfDictionary dic = null;
          if (!stack.isEmpty()) {
              dic = (PdfDictionary)stack.get(stack.size() - 1);
          }
          dic = mergeAttrib(dic, dict);
          stack.add(dic);
      }
docs: stack a level of dictionary. Merge in a dictionary from this level