arangosh> a1 = db.example.insert({"a" : 1});
{
"_id" : "example/18612116",
"_key" : "18612116",
"_rev" : "_VvTSDP2--_"
}
arangosh> a2 = db.example.update("example/18612115", { "x" : 1, "y" : 2 });
{
"_id" : "example/18612115",
"_key" : "18612115",
"_rev" : "_VvTSDP6--_",
"_oldRev" : "_VvTSDP2---"
}