code: def load_many(self, keys):
          # type: (Iterable[Hashable]) -> Promise
          
          if not isinstance(keys, Iterable):
              raise TypeError(
                  (
                      "The loader.loadMany() function must be called with Array<key> "
                      + "but got: {}."
                  ).format(keys)
              )
  
          return Promise.all([self.load(key) for key in keys])
docs: Loads multiple keys, promising an array of values
  
          >>> a, b = await my_loader.load_many([ 'a', 'b' ])
  
          This is equivalent to the more verbose:
  
          >>> a, b = await Promise.all([
          >>>    my_loader.load('a'),
          >>>    my_loader.load('b')
          >>> ])