 for computing the loss.
        </ul>
        <p>Information about whether it is training phase or test phase for batch norm is available in self.ph['phase_train']
        If preproc function is overridden, then self.inputs will have the outputs of preproc function.
        This function must return the network's output such as the predicted heatmaps.</p>

        <p>If the network output's heatmap and this is the only function that is overridden, then the network will trained using l2 loss between the tar