GObject.type_fundamental_next

function type_fundamental_next(): GObject.Type {
    // Gjs wrapper for g_type_fundamental_next()
}

Returns the next free fundamental type id which can be used to register a new fundamental type with GObject.type_register_fundamental. The returned type ID represents the highest currently registered fundamental type identifier.

Returns: the next available fundamental type ID to be registered, or 0 if the type system ran out of fundamental type IDs