If rhs holds the same alternative type as this object, move assign the contained value of rhs to the contained value of this object. Otherwise, destroy the contained value of this object (if any) and, if rhs holds a value, move‐construct the corresponding alternative of this object from the contained value of rhs. The allocators of this object and rhs both remain unchanged. If the construction of a new alternative object throws an exception, this variant object is left in a valueless by exception state. This operator participes in overload resolution only if all alternatives are move constructible and mvoe assignable. For simplicity of implementation, this method differs from the standard in the following ways: * conditional triviality is not implemented * constexpr is not implemented * noexcept specification is not implemented