isTuple
Determines if the given @type is a tuple type. This is true if the type string for @type starts with a '(' or if @type is %G_VARIANT_TYPE_TUPLE.
This function returns true for any indefinite type for which every definite subtype is a tuple type -- %G_VARIANT_TYPE_TUPLE, for example.
Return
true if @type is a tuple type
Since 2.24