arangosh> a1 = db.example.insert({ a : 1 });
{
"_id" : "example/15209",
"_key" : "15209",
"_rev" : "_VRerAle---"
}
arangosh> a2 = db._replace(a1, { a : 2 });
{
"_id" : "example/15209",
"_key" : "15209",
"_rev" : "_VRerAli---",
"_oldRev" : "_VRerAle---"
}
arangosh> a3 = db._replace(a1, { a : 3 });
[ArangoError 1200: precondition failed]