How cayley query the data belong to blank node

@dennwc @tamethecomplex thanks very much.

After I read up the
- https://github.com/tamethecomplex/tutorial-documents/blob/master/cayley/BeginnersGraphDatabaseSchemaDesign.md
- https://discourse.cayley.io/t/beginners-guide-to-schema-design-working-thread/436

and other materials, i designed and played with the following n-quads data:
```
"23TplPdS" .
"XXXX" .
"XXX" .
"lnshi" .
"M" .
"leonard.shi@xx.xx.xx" .
"false" .
_:l8 .
_:l8 "false" .
_:l8 "+65" .
_:l8 "+658672xxxx" .

"46Juzcyx" .
"xx.xx.xx_0000" .
"XXXX" .
"Leonard Shi 0000" .
"M" .
"leonard.shi+0000@xx.xx.xx" .
"false" .
_:l20 .
_:l20 "false" .
_:l20 "+65" .
_:l20 "+6586720000" .

"hwX6aOr7" .
"LEONARD__SHI_0001" .
"LEONARD SHI" .
"Leonard Shi 0001" .
"M" .
"leonard.shi+0001@xx.xx.xx" .
"false" .
_:l32 .
_:l32 "false" .
_:l32 "+65" .
_:l32 "+6586720001" .

.
.
```

but with Gremlin query `g.V("").Out().All()`, i get the following data:
```
{
"result": [
{
"id": "23TplPdS"
},
{
"id": "M"
},
{
"id": "XXX"
},
{
"id": "false"
},
{
"id": "_:l8"
},
{
"id": "Leonard Shi"
},
{
"id": "XXXX"
},
{
"id": "leonard.shi@xx.xx.xx"
}
]
}
```

the data belong to blank node `_:l8` are all gone from the result.

So how can I query the data which belong to blank node, or I design the model wrongly?