message: Remove the other sequence=
  Just realized that the List(sequence=) forwards to a list(sequence=) and would also break in Python 3.7.
diff: @@ -59,7 +59,7 @@ class HasList(training.Model):
  data_structures.List(
  list([core.Dense(11)]) + [core.Dense(12)]))
  self.layers_with_updates = data_structures.List(
  - sequence=(normalization.BatchNormalization(),))
  + (normalization.BatchNormalization(),))
  def call(self, x):
  aggregation = 0.
  