Missing compile step?

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I'm learning ROS for Turtlebot3, and am getting an error message that appears to tell me that I missed a compilation or build step. Perhaps I am missing an environment variable. Here are the key steps:

$ catkin_create_pkg wanderbot rospy geometry_msgs sensor_msgs

$ source ~/catkin_ws/devel/setup.bash 
pitosalas@ubuntu:~/catkin_ws/wanderbot/src$ ./redgreen.py 
from: can't read /var/mail/geometry_msgs.msg
./redgreen.py: line 6: syntax error near unexpected token `('
./redgreen.py: line 6: `cmd_vel_pub = rospy.Publisher('cmd_vel', Twist, queue_size=1) #<1>'

And looking for the missing geometry_msgs.msg:

pitosalas@ubuntu:/$ ls -l /opt/ros/kinetic/share/geometry_msgs/
total 12
drwxr-xr-x 2 root root 4096 Jul 23 18:39 cmake
drwxr-xr-x 2 root root 4096 Jul 23 18:39 msg
-rw-r--r-- 1 root root  794 Sep 30  2016 package.xml

And inside you can see the Twist.msg:

ls -l /opt/ros/kinetic/share/geometry_msgs/msg/
total 116
-rw-r--r-- 1 root root 119 Sep 30  2016 Accel.msg
-rw-r--r-- 1 root root  83 Sep 30  2016 AccelStamped.msg
-rw-r--r-- 1 root root 330 Sep 30  2016 AccelWithCovariance.msg
-rw-r--r-- 1 root root 124 Sep 30  2016 AccelWithCovarianceStamped.msg
-rw-r--r-- 1 root root 235 Sep 30  2016 Inertia.msg
-rw-r--r-- 1 root root  30 Sep 30  2016 InertiaStamped.msg
-rw-r--r-- 1 root root 367 Sep 30  2016 Point32.msg
-rw-r--r-- 1 root root  84 Sep 30  2016 Point.msg
-rw-r--r-- 1 root root  98 Sep 30  2016 PointStamped.msg
-rw-r--r-- 1 root root 107 Sep 30  2016 Polygon.msg
-rw-r--r-- 1 root root 104 Sep 30  2016 PolygonStamped.msg
-rw-r--r-- 1 root root  96 Sep 30  2016 Pose2D.msg
-rw-r--r-- 1 root root  85 Sep 30  2016 PoseArray.msg
-rw-r--r-- 1 root root 119 Sep 30  2016 Pose.msg
-rw-r--r-- 1 root root  79 Sep 30  2016 PoseStamped.msg
-rw-r--r-- 1 root root 323 Sep 30  2016 PoseWithCovariance.msg
-rw-r--r-- 1 root root 122 Sep 30  2016 PoseWithCovarianceStamped.msg
-rw-r--r-- 1 root root 108 Sep 30  2016 Quaternion.msg
-rw-r--r-- 1 root root 117 Sep 30  2016 QuaternionStamped.msg
-rw-r--r-- 1 root root 118 Sep 30  2016 Transform.msg
-rw-r--r-- 1 root root 337 Sep 30  2016 TransformStamped.msg
-rw-r--r-- 1 root root 115 Sep 30  2016 Twist.msg
-rw-r--r-- 1 root root  82 Sep 30  2016 TwistStamped.msg
-rw-r--r-- 1 root root 326 Sep 30  2016 TwistWithCovariance.msg
-rw-r--r-- 1 root root 124 Sep 30  2016 TwistWithCovarianceStamped.msg
-rw-r--r-- 1 root root 382 Sep 30  2016 Vector3.msg
-rw-r--r-- 1 root root 103 Sep 30  2016 Vector3Stamped.msg
-rw-r--r-- 1 root root 117 Sep 30  2016 Wrench.msg
-rw-r--r-- 1 root root  85 Sep 30  2016 WrenchStamped.msg
pitosalas@ubuntu:/$

Here's the full source of red green.py:

#example 1
#!/usr/bin/env python
import rospy
from geometry_msgs.msg import Twist

cmd_vel_pub = rospy.Publisher('cmd_vel', Twist, queue_size=1) #<1>
rospy.init_node('red_light_green_light')

red_light_twist = Twist() #<2>
green_light_twist = Twist()
green_light_twist.linear.x = 0.5 #<3>

driving_forward = False
light_change_time = rospy.Time.now()
rate = rospy.Rate(10)

while not rospy.is_shutdown():
  if ...