'Revokes the rate for the given key and path.'

def delete(self, key, path='/'):

    p = ('/' + path.strip('/'))
    q = 'delete    from    `rate`    where    key=?    and    path=?;'
    self.execute(q, (key, p))
    with self.lock:
        if self.cache.pop((key, p), False):
            self._n -= 1
