arangosh> a1 = db.example.insert({"a" : 1});
{
"_id" : "example/1134107346",
"_rev" : "1134107346",
"_key" : "1134107346"
}
arangosh> a2 = db.example.update("example/18612115", { "x" : 1, "y" : 2 });
{
"_id" : "example/18612115",
"_rev" : "1134500562",
"_key" : "18612115"
}