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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_model(self):
 """Build the model's computational graph."""

        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()