[tune][minor] formatting examples, fix travis (#5869)

* formatting

* formatting

doc/examples/plot_hyperparameter.py

@@ -70,6 +70,7 @@ def get_data_loaders(batch_size):
         shuffle=True)
     return train_loader, test_loader
 
+
 #######################################################################
 # Setup: Defining the Neural Network
 # ----------------------------------
@@ -130,6 +131,7 @@ def test(model, test_loader, device=torch.device("cpu")):
 
     return correct / total
 
+
 #######################################################################
 # Evaluating the Hyperparameters
 # -------------------------------
@@ -141,6 +143,7 @@ def test(model, test_loader, device=torch.device("cpu")):
 #
 # The ``@ray.remote`` decorator defines a remote process.
 
+
 @ray.remote
 def evaluate_hyperparameters(config):
     model = ConvNet()
@@ -152,6 +155,7 @@ def evaluate_hyperparameters(config):
     train(model, optimizer, train_loader)
     return test(model, test_loader)
 
+
 #######################################################################
 # Synchronous Evaluation of Randomly Generated Hyperparameters
 # ------------------------------------------------------------
@@ -159,7 +163,6 @@ def evaluate_hyperparameters(config):
 # We will create multiple sets of random hyperparameters for our neural
 # network that will be evaluated in parallel.
 
-
 # Keep track of the best hyperparameters and the best accuracy.
 best_hyperparameters = None
 best_accuracy = 0