class_docstr: Base class inherited by all seq2seq model classes.
  
  .. document private functions
  .. automethod:: _build
class_docstr_tok: ["Base","class","inherited","by","all","seq2seq","model","classes",".","..","document","private","functions","..","automethod",":",":","_build"]
code: def _get_train_op(self, loss):
      varlist = collect_trainable_variables(
          [
              self._src_embedder,
              self._tgt_embedder,
              self._encoder,
              self._connector,
              self._decoder,
          ]
      )
      return get_train_op(
          loss, variables=varlist, hparams=self._hparams.optimization
      )
  
imports: import tensorflow
  from texar.tf.models.model_base import ModelBase
  from texar.tf.losses.mle_losses import sequence_sparse_softmax_cross_entropy
  from texar.tf.data.data.paired_text_data import PairedTextData
  from texar.tf.core.optimization import get_train_op
  from texar.tf.hyperparams import HParams
  from texar.tf.utils import utils
  from texar.tf.utils.variables import collect_trainable_variables
label_desc: Use image node_id 10 for calling the Seq2seqBase obj's underlying member method code with example usage: obj._get_train_op(loss) and returns: get_train_op