Typo and unused import removal

Signed-off-by: Shane Loretz <[email protected]>

source/How-To-Guides/Migrating-from-ROS1/Migrating-Python-Package-Example.rst

@@ -645,7 +645,7 @@ Start with getting the time.
 ROS 2 nodes have a ``Clock`` instance.
 Replace the call to ``rospy.get_time()`` with ``node.get_clock().now()`` to get the current time from the node's clock.
 
-Next, replace the use of ``%`` with an f-string: ``f'hello world {self.get_clock().now()}'``.
+Next, replace the use of ``%`` with an f-string: ``f'hello world {node.get_clock().now()}'``.
 
 Finally, instantiate a ``std_msgs.msg.String()`` instance and assign the above to the ``data`` attribute of that instance.
 Your final code should look like this:
@@ -826,8 +826,6 @@ Your refactored code might look like this:
 
 .. code-block:: Python
 
-    import threading
-
     import rclpy
     from rclpy.node import Node
     from rclpy.executors import ExternalShutdownException