How to create empty tf.Variable. I try to make this but get errors

```
def __init__(self):
    super(ConcatLayer, self).__init__(dtype=tf.float64)
    self.total = tf.Variable(shape=tf.TensorShape([None, 3]), dtype=tf.float64)

```

ValueError: initial\_value must be specified.

Which initial\_value should I put?
Thx