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Response
  1. response.send() or response.jsonp()
    (Do not use response.end() it's very premitive)
  2. When you return something from a "then" callback, it's a bit magic. If you return a value, the next "then" is called with that value. However, if you return something promise-like, the next "then" waits on it, and is only called when that promise settles (succeeds/fails).
  3. .then(success function, errorfunction)