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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 forward(self, data_batch, is_train=None):
 """Forward computation for both two modules. It supports data batches with different shapes, such as different batch sizes or different image sizes. If reshaping of data batch relates to modification of symbol or module, such as changing image layout ordering or switching from training to predicting, module rebinding is required. See Also :meth:`BaseModule.forward`. Parameters data_batch : DataBatch Could be anything with similar API implemented. is_train : bool Default is ``None``, which means ``is_train`` takes the value of ``self.for_training``. """

        super(SVRGModule, self).forward(data_batch, is_train)

        if is_train:
            self._mod_aux.forward(data_batch, is_train)