Deconstructs a Variant instance.
Think of this function as an analogue to
The arguments that are expected by this function are entirely determined by
restricts the permissible types of this. It is an error to give a value with an incompatible type. See the
section on GVariant format strings. Please note that the syntax of the format string is very likely to be extended in the future.
format_string determines the C types that are used for unpacking the values and also determines if the values are copied or
borrowed, see the section on GVariant format strings.
a Variant instance
arguments, as per
a Variant format string