Changed python version in example code and code breakdown.

example_1.md

@@ -26,7 +26,7 @@ To stop the node from sending twist messages, type **Ctrl** + **c**.
 Below is the code which will send *Twist* messages to drive the robot forward.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 from geometry_msgs.msg import Twist
@@ -72,9 +72,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_10.md

@@ -49,7 +49,7 @@ python3 stow_command.py
 ### The Code
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import tf.transformations
@@ -124,9 +124,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 ```python
 import rospy
@@ -248,7 +248,7 @@ rotation:
 ### The Code
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 from geometry_msgs.msg import TransformStamped
@@ -296,9 +296,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 ```python
 import rospy

example_11.md

@@ -43,7 +43,7 @@ The gif below visualizes what happens when running the previous node.
 ### The Code
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import rospy
 import tf
 import sensor_msgs.point_cloud2 as pc2
@@ -124,9 +124,9 @@ if __name__=="__main__":
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 ```python
 import rospy

example_2.md

@@ -72,7 +72,7 @@ Change the topic name from the LaserScan display from */scan* to */filter_scan*.
 ### The Code
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 from numpy import linspace, inf
@@ -116,9 +116,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_3.md

@@ -31,7 +31,7 @@ To stop the node from sending twist messages, type **Ctrl** + **c** in the termi
 ### The Code
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 from numpy import linspace, inf, tanh
@@ -91,9 +91,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_4.md

@@ -26,7 +26,7 @@ The gif below demonstrates how to add a new *Marker* display type, and change th
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 from visualization_msgs.msg import Marker
@@ -84,9 +84,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_5.md

@@ -32,7 +32,7 @@ It's important to note that the arm has 4 prismatic joints and the sum of these
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import sys
@@ -87,9 +87,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_6.md

@@ -27,7 +27,7 @@ This will send a `FollowJointTrajectory` command to move Stretch's arm or head w
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import rospy
 import time
 import actionlib
@@ -152,9 +152,9 @@ if __name__ == '__main__':
 This code is similar to that of the [multipoint_command](https://github.com/hello-robot/stretch_tutorials/blob/main/src/multipoint_command.py) and [joint_state_printer](https://github.com/hello-robot/stretch_tutorials/blob/main/src/joint_state_printer.py) node. Therefore, this example will highlight sections that are different from those tutorials. Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_7.md

@@ -71,7 +71,7 @@ An image named **camera_image.jpeg** is saved in the **stored_data** folder in t
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import sys
@@ -125,9 +125,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python
@@ -225,7 +225,7 @@ The node will publish a new Image topic named */image_edge_detection*. This can
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import sys

example_8.md

@@ -27,7 +27,7 @@ The ReSpeaker will be listening and will start to interpret speech and save the
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import os
@@ -71,9 +71,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

example_9.md

@@ -53,7 +53,7 @@ To stop the node from sending twist messages, type **Ctrl** + **c** or say "**qu
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import math
 import rospy
@@ -266,9 +266,9 @@ if __name__ == '__main__':
 This code is similar to that of the [multipoint_command](https://github.com/hello-robot/stretch_tutorials/blob/main/src/multipoint_command.py) and [joint_state_printer](https://github.com/hello-robot/stretch_tutorials/blob/main/src/joint_state_printer.py) node. Therefore, this example will highlight sections that are different from those tutorials. Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python

follow_joint_trajectory.md

@@ -30,7 +30,7 @@ This will send a `FollowJointTrajectory` command to stow Stretch's arm.
 ### The Code
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 from control_msgs.msg import FollowJointTrajectoryGoal
@@ -88,9 +88,9 @@ if __name__ == '__main__':
 Now let's break the code down.
 
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 ```
-Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
+Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python3 script.
 
 
 ```python
@@ -181,7 +181,7 @@ This will send a list of `JointTrajectoryPoint` message types to move Stretch's
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import time
@@ -335,7 +335,7 @@ The joint, *joint_gripper_finger_left*, is only needed when actuating the grippe
 
 ### The Code
 ```python
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import rospy
 import time