foreach my $arg (@ARGV) {
    if( $arg =~ /^-B(\d+)$/ ) {  # months Before
	$before = $1;
    } elsif( $arg =~ /^-B$/ ) {
	$before = shift( @ARGV );
	if( $before !~ /^\d+/ ) {
	    die "Bad before argument ($before)\n";
	}

##</code><code>##

/$ /usr/local/bin/cal2.pl -B 4
Uncaught exception from user code:
	Bad before argument (-B)