code: public Layout getGeneration(int generation) throws FetchNoneException, FetchException {
          try {
              Storage<StoredLayoutEquivalence> equivStorage =
                  mLayoutFactory.mRepository.storageFor(StoredLayoutEquivalence.class);
              StoredLayoutEquivalence equiv = equivStorage.prepare();
              equiv.setStorableTypeName(getStorableTypeName());
              equiv.setGeneration(generation);
              if (equiv.tryLoad()) {
                  generation = equiv.getMatchedGeneration();
              }
          } catch (RepositoryException e) {
              throw e.toFetchException();
          }
  
          return new Layout(mLayoutFactory, getStoredLayoutByGeneration(generation));
      }
docs: Returns the layout for a particular generation of this layout's type.
  
  @throws FetchNoneException if generation not found