Fix function params indentation (#446)

And add return type.

Signed-off-by: Christophe Bedard <[email protected]>

Author: christophebedard

launch_testing_ros/launch_testing_ros/wait_for_topics.py

@@ -52,7 +52,7 @@ def method_2():
             wait_for_topics.shutdown()
     """
 
-    def __init__(self, topic_tuples, timeout=5.0, messages_received_buffer_length=10):
+    def __init__(self, topic_tuples, timeout=5.0, messages_received_buffer_length=10) -> None:
         self.topic_tuples = topic_tuples
         self.timeout = timeout
         self.messages_received_buffer_length = messages_received_buffer_length
@@ -121,8 +121,8 @@ class _WaitForTopicsNode(Node):
     """Internal node used for subscribing to a set of topics."""
 
     def __init__(
-            self, name='test_node', node_context=None, messages_received_buffer_length=None
-    ):
+        self, name='test_node', node_context=None, messages_received_buffer_length=None
+    ) -> None:
         super().__init__(node_name=name, context=node_context)  # type: ignore
         self.msg_event_object = Event()
         self.messages_received_buffer_length = messages_received_buffer_length