code: def build_model(self):
          
          with tf.variable_scope(
                  "model", reuse=None, initializer=self.initializer):
              self._create_placeholders()
              self._create_rnn_cells()
              self._create_initstate_and_embeddings()
              self._create_rnn_architecture()
              self._create_optimizer_node()
docs: Build the model's computational graph.