Returns a default initializer for the weights of a convolutional module.

def create_weight_initializer(fan_in_shape, dtype=tf.float32):
  """Returns a default initializer for the weights of a convolutional module."""
  stddev = 1 / math.sqrt(np.prod(fan_in_shape))
  return tf.truncated_normal_initializer(stddev=stddev, dtype=dtype)