tasklet control flow example

gistfile1.py

# from https://developers.google.com/appengine/docs/python/ndb/async

@ndb.tasklet
def get_cart_async(acct):
  cart = yield CartItem.query(CartItem.account == acct.key).fetch_async()
  yield ndb.get_multi_async([item.inventory for item in cart])
  raise ndb.Return(cart)

@ndb.tasklet
def get_offers_async(acct):
  offers = yield SpecialOffer.query().fetch_async(10)
  yield ndb.get_multi_async([offer.inventory for offer in offers])
  raise ndb.Return(offers)

@ndb.tasklet
def get_cart_plus_offers(acct):
  cart, offers = yield get_cart_async(acct), get_offers_async(acct)
  raise ndb.Return((cart, offers))