glib:variant-dict-lookup-value (dict key &optional vtype)

dict -- a g:variant-dict instance
key -- a string for the key to look up in the dictionary
vtype -- a g:variant-type instance for the expected type

Looks up a value in a g:variant-dict instance. If key is not found in the dictionary, nil is returned.

The vtype string specifies what type of value is expected. If the value associated with key has a different type then nil is returned.

If the key is found and the value has the correct type, it is returned. If vtype was specified then any non-nil return value will have this type.