If you need to adapt a script, it is sometimes best to create a new script and copy in the text from the original script and edit it here.
In this example we have copied the text / commands from a scototaxis script, created a new script, called scototaxis_2, and pasted in the original script. From here we edit the script. In this case we want to update the script so that it runs for 30 minutes (i.e. 1800 seconds) and change the lights displayed on the screen so that the same half of the screen is light during the whole experiment.
Adapting a script tutorial