: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
>types
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.

:example
DValue u;
u["name"] = "Ada";
print(u.has("name") ? "has name" : "no name", " / ", u.has("age") ? "has age" : "no age", "\n");
