:sig
bool DValue::has(String s) const

:params
s : child key to test
return value : true when the dereferenced value is map-shaped and contains the key

:see
0_DValue
2_DValue_key
2_DValue_get_by_path

:content
Checks for a child key without creating it. Returns false for scalars and missing keys.

```cpp
if(context.props.has("title")) print(context.props["title"].to_string());
```