Available since: Gideros 2011.6
When called with a file name, it opens the named file (in text mode), and sets its handle as the default output file.
When called with a file handle, it simply sets this file handle as the default output file.
When called without parameters, it returns the current default output file.
(file) = io.output(file)
In case of errors this function raises the error, instead of returning an error code.
file: (file) file object to use as default output optional
Returns (file) default output file object