When the WIF is entered, I'm using the steem-js method to convert the private key to a public key, and then comparing that public key to what is on the account you entered.

I assume this same method could be done in steem-python.

http://steem.readthedocs.io/en/latest/low_level.html?highlight=wif#steembase.account.PrivateKey

That and the method below it would be a good starting point.