Show-InstallationWelcome - Option for not proceeding with install

Hi All, I would like to have an option to not proceed with an install at the Start. I can have a message advising what will happen, i.e. " “blah” app will me installed, would you like to proceed?" I can have an Ok button,but how do i add an “No” or “Cancel” option?
Thanks again.

In the “Pre-installation” section of the PS1:

$userResponse = show-installationprompt -message “Message text here” -buttonrighttext “Cancel” -buttonlefttext “OK”
If($userResponse -eq ‘Cancel’) {}
Else { Do stuff… }