my( $arg )= @_;
    my $fh;
    if(  ref( $arg )  ) {
        $fh= $arg;
    } elsif(  "GLOB" eq $arg  ) {
        $fh= \$arg;
        # or  $fh= *{$arg}{IO};
    } else {
        # It is a plain string.  If you want to
        # treat it as the name of a glob, then
        # you'll need to check for /::|'/ and
        # prepend caller().'::', unless it is
        # special like 'STDOUT'.
        # You'll also need 'no strict;' here.
        ...
    }