Save things for queue creation

class Layer(object):

  def __init__(self, **kwargs):

    if "name" not in kwargs:

      self.name = "%s%s" % (self.__class__.__name__, self._random_name())

    super().__init__(**kwargs)

  def __call__(self, *parents):

    self.out_tensor = tf.placeholder(tf.float32, shape=self.t_shape)

    if not self.pre_queue:

      queue = parents[0]

      placeholder = queue.out_tensors[self.get_pre_q_name()]

      self.out_tensor = tf.placeholder_with_default(placeholder, self.shape)

      return self.out_tensor

    self.out_tensor = tf.placeholder(tf.float32, shape=self.shape)

    return self.out_tensor

  def create_pre_q(self, batch_size):

    if self.pre_queue:

      raise ValueError("Input is already pre_q")

    q_shape = (batch_size,) + self.shape[1:]

    return Input(shape=q_shape, name="%s_pre_q" % self.name, pre_queue=True)

  def get_pre_q_name(self):

    if self.pre_queue:

      raise ValueError("You are already pre_q")

    return "%s_pre_q" % self.name

class LossLayer(Layer):