code: def _make_tuple(x):
    
    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,)
docs: TF has an obnoxious habit of being lenient with single vs tuple.