How can I write a query with unknown levels nests?

[ooo2003003v2]

Hello there.
I have a problem with my query. I wanna output a nested object with unknown levels like the one down below but I cant make my fragment reference itself. Any idea how to solve it???

{
"account":"",
"children":[
{
"account":"",
"children":[
{
"account":"",
"children":[
{
"account":"",
"children":[
...
]
}
]
}
]
},
{
"account":"",
"children":[
...
]
},
{
"account":"",
"children":[
...
]
}
]
}