$sort in mongoose code example

Example: mongoose find sort

Post.find({}).sort('test').exec(function(err, docs) { ... });
Post.find({}).sort([['date', -1]]).exec(function(err, docs) { ... });
Post.find({}).sort({test: 1}).exec(function(err, docs) { ... });
Post.find({}, null, {sort: {date: 1}}, function(err, docs) { ... });