code: public Diff add(final Diff paramChange) {
          assert paramChange != null;
          final ITreeData item =
              paramChange.getDiff() == EDiff.DELETED ? paramChange.getOldNode() : paramChange.getNewNode();
          if (mChangeByNode.containsKey(item)) {
              return paramChange;
          }
  
          mChanges.add(paramChange);
          return mChangeByNode.put(item, paramChange);
      }
docs: Adds a change to the edit script.
  
  @param paramChange
  {@link Diff} reference
  @return the change