makes FileOrStream the current output stream.
If there is an open output stream currently associated with the filename,
and that stream was opened by
tell/1, then it is made the current output
Otherwise, the specified file is opened for output and made the
current output stream. If the file does not exist, it is created. If
it is not possible to open the file (because of protections, for
tell/1 raises an exception.
Different file names (names that do not unify) represent different
streams (even if they correspond to the same file). Therefore,
./food represent the same file, the following
sequence will open two streams, both connected to the same file:
tell(food) ... tell('./food')
It is important to remember to close streams when you have finished with
told/0 (ref-iou-sfh-cst) or