[turtle1_tf_broadcaster-4] process has died

edit

I tried to follow the tutorial from here :

http://www.ros.org/wiki/tf/Tutorials/...

But there's some error and a process died. This is the full message :

nehal@nehal-Inspiron-5559:~$ roslaunch turtle_tf turtle_tf_demo.launch
... logging to /home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/roslaunch-nehal-Inspiron-5559-20520.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://nehal-Inspiron-5559:34279/

SUMMARY
========

PARAMETERS
 * /rosdistro: kinetic
 * /rosversion: 1.12.12
 * /scale_angular: 2.0
 * /scale_linear: 2.0
 * /turtle1_tf_broadcaster/turtle: turtle1

 * /turtle2_tf_broadcaster/turtle: turtle2

NODES
  /
    sim (turtlesim/turtlesim_node)
    teleop (turtlesim/turtle_teleop_key)
    turtle1_tf_broadcaster (turtle_tf/turtle_tf_broadcaster.py)
    turtle2_tf_broadcaster (turtle_tf/turtle_tf_broadcaster.py)
    turtle_pointer (turtle_tf/turtle_tf_listener.py)

auto-starting new master

process[master]: started with pid [20530]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to bdcfe396-49e2-11e8-8565-780cb8563dc1
process[rosout-1]: started with pid [20543]
started core service [/rosout]
process[sim-2]: started with pid [20550]

process[teleop-3]: started with pid [20560]
process[turtle1_tf_broadcaster-4]: started with pid [20562]
Reading from keyboard
process[turtle2_tf_broadcaster-5]: started with pid [20574]
---------------------------
Use arrow keys to move the turtle.

process[turtle_pointer-6]: started with pid [20579]
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/turtle_tf/turtle_tf_broadcaster.py", line 37, in <module>
    import tf
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/tf/__init__.py", line 28, in <module>
    from tf2_ros import TransformException as Exception, ConnectivityException, LookupException, ExtrapolationException
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/tf2_ros/__init__.py", line 38, in <module>
    from tf2_py import *
    from tf2_ros import TransformException as Exception, ConnectivityException, LookupException, ExtrapolationException
  File "/opt/ros/kinetic/lib/turtle_tf/turtle_tf_broadcaster.py", line 37, in <module>
    import tf
[turtle1_tf_broadcaster-4] process has died [pid 20562, exit code 1, cmd /opt/ros/kinetic/lib/turtle_tf/turtle_tf_broadcaster.py __name:=turtle1_tf_broadcaster __log:=/home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/turtle1_tf_broadcaster-4.log].
log file: /home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/turtle1_tf_broadcaster-4*.log
[turtle2_tf_broadcaster-5] process has died [pid 20574, exit code 1, cmd /opt/ros/kinetic/lib/turtle_tf/turtle_tf_broadcaster.py __name:=turtle2_tf_broadcaster __log:=/home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/turtle2_tf_broadcaster-5.log].
log file: /home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/turtle2_tf_broadcaster-5*.log
[turtle_pointer-6] process has died [pid 20579, exit code 1, cmd /opt/ros/kinetic/lib/turtle_tf/turtle_tf_listener.py __name:=turtle_pointer __log:=/home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/turtle_pointer-6.log].
log file: /home/nehal/.ros/log/bdcfe396-49e2-11e8-8565-780cb8563dc1/turtle_pointer-6*.log