keras/src/backend/torch/optimizers/torch_parallel_optimizer.py/TorchParallelOptimizer/_backend_update_step
class TorchParallelOptimizer:    def _backend_update_step(self, grads, trainable_variables, learning_rate):
        self._parallel_update_step(
            grads,
            trainable_variables,
            learning_rate,
        )