code: def _create_variables_pretrain(self):
          
          for l, layer in enumerate(self.layers):
              self.encoding_w_[l] = tf.Variable(
                  self.encoding_w_[l], name='enc-w-{}'.format(l))
              self.encoding_b_[l] = tf.Variable(
                  self.encoding_b_[l], name='enc-b-{}'.format(l))
docs: Create model variables (previous unsupervised pretraining).
  
          :return: self