'Expire a HIT that is no longer needed.
The effect is identical to the HIT expiring on its own. The
HIT no longer appears on the Mechanical Turk web site, and no
new Workers are allowed to accept the HIT. Workers who have
accepted the HIT prior to expiration are allowed to complete
it or return it, or allow the assignment duration to elapse
(abandon the HIT). Once all remaining assignments have been
submitted, the expired HIT becomes"reviewable", and will be
returned by a call to GetReviewableHITs.'

def expire_hit(self, hit_id):

    params = {'HITId': hit_id}
    return self._process_request('ForceExpireHIT', params)
