Fix format to fit flake8

Author: jiseongHAN

rl_algorithms/example/__init__.py renamed to example/__init__.py

@@ -3,7 +3,7 @@
    This is example for using custom agent.
    In this example, custom agent use state as exponential.
    You can customize any function e.g) select_aciton, train ... etc.
-   
+
    To use custom agent just decorate class to build and import in main function.
 
     - Author: Jiseong Han

rl_algorithms/example/custom_agent.py renamed to example/custom_agent.py

@@ -168,12 +168,13 @@ def main(env):
 
 
 if __name__ == "__main__":
-    ###############################################################################################
+    ###################################################################################
     # To use custom agent and learner, import custom agent and learner.
-    from custom_agent import CustomDQN
-    from custom_learner import CustomDQNLearner
+    #
+    from custom_agent import CustomDQN  # noqa: F401
+    from custom_learner import CustomDQNLearner  # noqa: F401
 
     # Declare custom environment here.
     env = CustomEnv()
-    ###############################################################################################
+    ###################################################################################
     main(env)