use testChangeStreams;
db.dropDatabase();

// Example 1
print("1. First cursor value: ");
db.changes.insertOne({test: "a"});
var cursor1 = db.changes.aggregate([ { $changeStream: { fullDocument: "none"} } ]);

var next = null;
if (cursor1.hasNext()) {
    next = cursor1.next();
}
printjson(next);

// Example 2
print("2. Lookup enabled: ");
var cursor2 = db.changes.aggregate([{$changeStream: {fullDocument: "lookup"} }]);

while (cursor2.hasNext()) {
    next = cursor2.next();
}
db.changes.updateOne({test: "a"}, {$set: {test: "b"}});
next = cursor2.next();  // Segfaults
printjson(next);