:title
DValue::operator[]

:sig
DValue& DValue::operator[](String s)

:params
s : child key to return or create
return value : reference to the child node

:see
0_DValue
2_DValue_get_or_create
2_DValue_key
2_DValue_has

:content
Returns a mutable reference to a child, creating the child when it does not already exist. If this value is an internal reference, the operation is forwarded to the target. This has the same creation behavior as `get_or_create()`, so use `has()`, `key()`, or `get_by_path()` for non-mutating reads.

```cpp
context.call["user"]["name"] = "Ada";
```
