if ( not $code ) {
        $code       = $unit;
    };
    if ( $args and ref $args ) {
        @args       = @$args;
        $code       .= q{(@args)};
    }
    else {
        @args       = ();
    };
    if ( $argv and ref $argv ) {
        @ARGV       = @$argv;
    }


##</code><code>##

    if ( $A ) {
        if ( $B ) {
            {...}
        }
        else {
            {...}
        };
    }
    else {
        if ( $B ) {
            {...}
        }
        else {
            {...}
        };
    };

##</code><code>##

    # Four-outcome tree
    my $cf      = !!$code;
    my $af      = !!( $args and ref $args );
    if    (  $cf &&  $af ) {
        @ARGV       = @$args;
    } 
    elsif (  $cf && !$af ) {
        @args       = ();
    } 
    elsif ( !$cf &&  $af ) {
        @args       = @$args;
        $code       = $unit . q{(@args)};
    } 
    elsif ( !$cf && !$af ) {
        @args       = ();
        $code       = $unit . q{()};
    } 
    else { die 'Fifth element!' };