Move-assign a stream handle from a handle of another executor type.
template< typename Executor1> constraint< is_convertible< Executor1, Executor >::value, basic_stream_handle & >::type operator=( basic_stream_handle< Executor1 > && other);
This assignment operator moves a stream handle from one object to another.
The other stream handle object from which the move will occur.
Following the move, the moved-from object is in the same state as if
constructed using the basic_stream_handle(const executor_type&)
constructor.