arangosh> a1 = db.example.insert({ a : 1 });
{
"_id" : "example/17344",
"_key" : "17344",
"_rev" : "_WBDp_Dy--_"
}
arangosh> a2 = db._update(a1, { b : 2 });
{
"_id" : "example/17344",
"_key" : "17344",
"_rev" : "_WBDp_D2--_",
"_oldRev" : "_WBDp_Dy--_"
}
arangosh> a3 = db._update(a1, { c : 3 });
[ArangoError 1200: precondition failed]