human
Complete this python program:
def _chain_future(source, destination):
assistant
#Here is the Python program you requested.

    """Chain two futures so that when one completes, so does the other.
    The result (or exception) of source will be copied to destination.
    If destination is cancelled, source gets cancelled too.
    Compatible with both asyncio.Future and concurrent.futures.Future.
    """
    if (not isinstance(source, (Future, concurrent.futures.Future))):
        raise TypeError('A    future    is    required    for    source    argument')
    if (not isinstance(destination, (Future, concurrent.futures.Future))):
        raise TypeError('A    future    is    required    for    destination    argument')
    source_loop = (source._loop if isinstance(source, Future) else None)
    dest_loop = (destination._loop if isinstance(destination, Future) else None)
    def _set_state(future, other):
        if isinstance(future, Future):
            _copy_future_state(other, future)
        else:
            _set_concurrent_future_state(future, other)
    def _call_check_cancel(destination):
        if destination.cancelled():
            if ((source_loop is None) or (source_loop is dest_loop)):
                source.cancel()
            else:
                source_loop.call_soon_threadsafe(source.cancel)
    def _call_set_state(source):
        if ((dest_loop is None) or (dest_loop is source_loop)):
            _set_state(destination, source)
        else:
            dest_loop.call_soon_threadsafe(_set_state, destination, source)
    destination.add_done_callback(_call_check_cancel)
    source.add_done_callback(_call_set_state)