message: [tf.data] More actionable error message when passing a list to `Dataset.zip()`.
diff: @@ -933,6 +933,16 @@ class ZipDataset(Dataset):
  def __init__(self, datasets):
  """See `Dataset.zip()` for details."""
  super(ZipDataset, self).__init__()
  + for ds in nest.flatten(datasets):
  + if not isinstance(ds, Dataset):
  + if isinstance(ds, list):
  + message = ("The argument to `Dataset.zip()` must be a nested "
  + "structure of `Dataset` objects. Nested structures do not "
  + "support Python lists; please use a tuple instead.")
  + else:
  + message = ("The argument to `Dataset.zip()` must be a nested "
  + "structure of `Dataset` objects.")
  + raise TypeError(message)
  self._datasets = datasets
  def _as_variant_tensor(self):
  