arangosh> a1 = db.example.insert({"a" : 1});
{
"_id" : "example/4224622523",
"_rev" : "4224622523",
"_key" : "4224622523"
}
arangosh> a2 = db.example.update("example/18612115", { "x" : 1, "y" : 2 });
{
"_id" : "example/18612115",
"_rev" : "4225015739",
"_key" : "18612115"
}