If a value for key in asv is present and is a string, return it.
Otherwise return null.
The returned value is not copied, and is only valid as long as the value for key in asv is not removed or
altered. Copy it with strdup if you need to keep it for longer.
| asv |
A GHashTable where the keys are strings and the values are GValues |
| key |
The key to look up |
|
the string value of |