It's built into the Meraki Python library, you can see it in the github repository.
If you mean the additional one I sometimes add to scripts that can generate lots of calls, just put the library call inside a loop, then use try/except to detect a 429 (i.e. the internal wait/retry in the library call has had too many retries), if there's a 429, wait a while, then do continue to restart the loop, if all went well, exit the loop.
I use an increasing delay inside the loop, ten seconds first time, increasing exponentially to about 5 minutes, after that give up and exit as there's either a fault or someone else is constantly hitting the API and using up the call budget.