This is a class for null file handles. Calling a constructor of this
class always succeeds, returning a new null file handle. Writing to
any object of this class is always a no-operation, and returns true.
Reading from any object of this class is always no-operation, and
returns empty-string or empty-list, as appropriate.

You could say:
       open(NULL, '>/dev/null') || die "WHAAT?! $!";
and get a null FH that way.  But not everyone is using an OS
that has a /dev/null