code: public List<Key> put(Transaction transaction, Iterable<Entity> entities) {
  		return datastore.put(transaction, entities);
  	}
docs: Puts the specified App Engine Datastore entities into the datastore
  within the specified {@code Transaction}.
  
  @param transaction The transaction to put the entities.
  @param entities The entities to be put.
  @return The keys allocated to the stored entities.