I have read your document.I can help you to do this work.
I notice you have two url to GET. one is [login to view URL] to get all cities, and the other is [login to view URL]<CITY NAME> to get city bike docks. then Fetch method will get which one.
1 NewFetcher() get [login to view URL], and fetch() get [login to view URL]
2 fetch() can get two kind of url by parameter url.
Thank you.