For the history of this, see: <a href="https:&#x2F;&#x2F;code.activestate.com&#x2F;lists&#x2F;python-checkins&#x2F;32587&#x2F;" rel="nofollow">https:&#x2F;&#x2F;code.activestate.com&#x2F;lists&#x2F;python-checkins&#x2F;32587&#x2F;</a><p>This is actually just a unique object used for an object identity check, so that instances of the HMAC class can copy themselves and tell the copy to not bother initializing its internal state before that state gets overwritten.  It&#x27;s not in any way a &quot;key&quot; in the cryptographic sense.<p>Current events, on the other hand, make it a rather poor variable name in hindsight.