see transcript below:

> db.test.find()
> db.test.save(

{a: 1, b:2, c:3}

)
> db.test.save(

{r: 4, s:5, t:6}

)
> db.test.find()

{"_id" : ObjectId( "4aa12a88820c00000000615a") , "a" : 1 , "b" : 2 , "c" : 3} {"_id" : ObjectId( "4aa12a94820c00000000615b") , "r" : 4 , "s" : 5 , "t" : 6}

> k=db.test.find()

{"_id" : ObjectId( "4aa12a88820c00000000615a") , "a" : 1 , "b" : 2 , "c" : 3} {"_id" : ObjectId( "4aa12a94820c00000000615b") , "r" : 4 , "s" : 5 , "t" : 6}

> k
> k.hasNext()
false
> k.next()
/* CRASH */