Hi,

I've just been going through the tf2 tutorial for ros2 foxy and I'm having a lot of trouble with the launch files (and I'm just copy/pasting the files as they come in the tutorial), they throw this error:

---

/devws# ros2 launch learningtf2py turtletf2demo.launch.py [INFO] [launch]: All log files can be found below /root/.ros/log/2022-08-03-18-29-24-875095-7fee628f4b5c-152 [INFO] [launch]: Default logging verbosity is set to INFO Task exception was never retrieved future: <Task finished name='Task-2' coro=<LaunchService.processoneevent() done, defined at /opt/ros/foxy/lib/python3.8/site-packages/launch/launchservice.py:226> exception=AttributeError("'ellipsis' object has no attribute 'describesubentities'")> Traceback (most recent call last): File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launchservice.py", line 228, in processoneevent await self.processevent(nextevent) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launchservice.py", line 248, in processevent visitallentitiesandcollectfutures(entity, self.context)) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visitallentitiesandcollectfuturesimpl.py", line 45, in visitallentitiesandcollectfutures futurestoreturn += visitallentitiesandcollectfutures(subentity, context) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visitallentitiesandcollectfuturesimpl.py", line 45, in visitallentitiesandcollectfutures futurestoreturn += visitallentitiesandcollectfutures(subentity, context) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visitallentitiesandcollectfuturesimpl.py", line 38, in visitallentitiesandcollectfutures subentities = entity.visit(context) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/action.py", line 108, in visit return self.execute(context) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/actions/includelaunchdescription.py", line 145, in execute declaredlauncharguments = launchdescription.getlauncharguments() File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launchdescription.py", line 126, in getlauncharguments processentities(self.entities, _conditionalinclusion=conditionalinclusion) File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launchdescription.py", line 120, in processentities entity.describesubentities(), _conditionalinclusion=False) AttributeError: 'ellipsis' object has no attribute 'describesubentities'

---

I've verified that the error is not related to my installation as same thing happens in a docker container. I'm kind of in a hurry, do you have any clue what's going on? the launch file is:

---

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration

from launch_ros.actions import Node

def generate_launch_description():
    return LaunchDescription([
        ...,
        DeclareLaunchArgument(
            'target_frame', default_value='turtle1',
            description='Target frame name.'
        ),
        Node(
            package='learning_tf2_py',
            executable='turtle_tf2_broadcaster',
            name='broadcaster2',
            parameters=[
                {'turtlename': 'turtle2'}
            ]
        ),
        Node(
            package='learning_tf2_py',
            executable='turtle_tf2_listener',
            name='listener',
            parameters=[
                {'target_frame': LaunchConfiguration('target_frame')}
            ]
        ),
    ])

---

---

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration

from launch_ros.actions import Node


def generate_launch_description():
    return LaunchDescription([
        DeclareLaunchArgument(
            'target_frame', default_value='turtle1',
            description='Target frame name.'
        ),
        Node(
            package='turtlesim',
            executable='turtlesim_node',
            name='sim'
        ),
        Node(
            package='turtle_tf2_py',
            executable='turtle_tf2_broadcaster',
            name='broadcaster1',
            parameters=[
                {'turtlename': 'turtle1'}
            ]
        ),
        Node(
            package='turtle_tf2_py',
            executable='turtle_tf2_broadcaster',
            name='broadcaster2',
            parameters=[
                {'turtlename': 'turtle2'}
            ]
        ),
        Node(
            package='turtle_tf2_py',
            executable='turtle_tf2_listener',
            name='listener',
            parameters=[
                {'target_frame': LaunchConfiguration('target_frame')}
            ]
        ),
    ])