code: def build_model(self, n_features, n_classes):
          
          self._create_placeholders(n_features, n_classes)
          self._create_layers(n_classes)
  
          self.cost = self.loss.compile(self.mod_y, self.input_labels)
          self.train_step = self.trainer.compile(self.cost)
          self.accuracy = Evaluation.accuracy(self.mod_y, self.input_labels)
docs: Create the computational graph of the model.
  
          :param n_features: Number of features.
          :param n_classes: number of classes.
          :return: self