# Implements flickr.photos.getRecent and flickr.photos.search
  def photos(*criteria)
    photos = (criteria[0]) ? photos_search(criteria[0]) : photos_getRecent
    photo_collection = photos['photos']['photo']

    # if only one photo, there's no array of photos; create the one photo
    return [Photo.new(photo_collection['id'])] unless photo_collection.kind_of? Array

    # otherwise, create all the photos
    photo_collection.collect { |photo| Photo.new(photo['id']) }
  end