code: function(consumerKey, done) {
      db.clients.findByConsumerKey(consumerKey, function(err, client) {
        if (err) { return done(err); }
        if (!client) { return done(null, false); }
        return done(null, client, client.consumerSecret);
      });
    }
docs: consumer callback  This callback finds the registered client associated with `consumerKey`. The client should be supplied to the `done` callback as the second argument, and the consumer secret known by the server should be supplied as the third argument.  The `ConsumerStrategy` will use this secret to validate the request signature, failing authentication if it does not match.