What is the best way to migrate In-app billing Version 2 to Version 3?

What is the best way to migrate In-app billing Version 2 to Version 3?

I received an email from Google Wallet on Friday saying:
Our records indicate you are a Play Apps developer who may be using Google
Checkout APIs for >notifications or reporting. On May 20, we announced
that we will be replacing these APIs.
We provided replacement Play APIs, as of July 25, and anyone using the
Checkout >notifications or reporting APIs needs to implement the Play APIs
by August 22 to prevent >disruption to your scripts.
If you used the Checkout API for notifications, use the Play Purchase
Status API. If you >used the Checkout API for reporting, you can automate
the download of your estimated sales >and earning reports via the gsutil
utility
I assume that the Google Checkout APIs I must be using are in relation to
the In-app Billing Version 2 implementation that I have. It relies on the
Billing Service to share interprocess communications with the Google Play
Store app via local notifications. So I believe that I am supposed to look
into the Play Purchase Status API. I looked into it, but I wonder if there
are any tutorials or better documentation for the process of transitioning
from the old In-app Billing Version 2 to use the new Google Play Developer
API. Any info would be great.