arangosh> a1 = db.example.insert({ a : 1 });
{
"_id" : "example/110724",
"_key" : "110724",
"_rev" : "_YDCrnEu--_"
}
arangosh> a2 = db._update(a1, { b : 2 });
{
"_id" : "example/110724",
"_key" : "110724",
"_rev" : "_YDCrnEy--_",
"_oldRev" : "_YDCrnEu--_"
}
arangosh> a3 = db._update(a1, { c : 3 });
[ArangoError 1200: precondition failed]