def add_atomic_update(clazz, updates={})
      documents = updates.map { |id, m| prepare_atomic_update(clazz, id, m) }
      add_batch_documents(documents)
    end
def add_atomic_update(clazz, updates={})
      documents = updates.map { |id, m| prepare_atomic_update(clazz, id, m) }
      add_batch_documents(documents)
    end
Construct a representation of the given class instances for atomic properties update
 and send it to the connection for indexing

 ==== Parameters

 clazz<Class>:: the class of the models to be updated
 updates<Hash>:: hash of updates where keys are model ids
                 and values are hash with property name/values to be updated