message: [Example] update example code
diff: @@ -101,8 +101,7 @@ def top_level_task():
  # t now contains entire model. Add single-neuron output
  t = ffmodel.dense(t, 1)
  - optimizer = SGDOptimizer(ffmodel, 1e-3)
  - ffmodel.set_sgd_optimizer(optimizer)
  + ffmodel.optimizer = SGDOptimizer(ffmodel, 1e-3)
  ffmodel.compile(loss_type=LossType.LOSS_MEAN_SQUARED_ERROR_AVG_REDUCE, metrics=[MetricsType.METRICS_ACCURACY], comp_mode=CompMode.INFERENCE)
  ffmodel.init_layers()
  ts_start = ffconfig.get_current_time()
  