Is it possible to point from one collection's item's value to another collection's item?

example:

```
db.col2.save( { value: 'test' } );
db.col1.save( { title: 'testing, something: [code to point to another collection's item] } );

db.col1.find().toArray()

[
        {
                "_id" : ObjectId([someobjectidhere]),
                "title" : "testing",
                "something": {
                        "value": "test"
                }
        }
]

```