code: func (h *Handler) GetContent(feed *Feed) (storage.Address, []byte, error) {
  	if feed == nil {
  		return nil, nil, NewError(ErrInvalidValue, "feed is nil")
  	}
  	feedUpdate := h.get(feed)
  	if feedUpdate == nil {
  		return nil, nil, NewError(ErrNotFound, "feed update not cached")
  	}
  	return feedUpdate.lastKey, feedUpdate.data, nil
  }
docs: // GetContent retrieves the data payload of the last synced update of the feed