def _make_tuple(x):
  """TF has an obnoxious habit of being lenient with single vs tuple."""
  if isinstance(x, prettytensor.PrettyTensor):
    if x.is_sequence():
      return tuple(x.sequence)
    else:
      return (x.tensor,)
  elif isinstance(x, tuple):
    return x
  elif (isinstance(x, collections.Sequence) and
        not isinstance(x, six.string_types)):
    return tuple(x)
  else:
    return (x,)
TF has an obnoxious habit of being lenient with single vs tuple.