def each(&block)
      collection.each do |id, url|
        object = cached(id) { klass.from_url(url, prefix) }
        block.call(object) if block
      end
    end
def each(&block)
      collection.each do |id, url|
        object = cached(id) { klass.from_url(url, prefix) }
        block.call(object) if block
      end
    end
The custom iterator for looping over each object in this collection. For
 more information, please see the +Enumerator+ module in Ruby core.