use strict;
use CGI;
my $q = CGI->new;

my $good_method = "param";
my $bad_method = "param('foo')";
print $q->$good_method( 'foo' );
print $q->$bad_method;

##</code><code>##

@commands = (
  ['add_node','W1'],
  ['add_node','W2'],
  ['add_edge,'W2' => 'W1']
);

use GraphViz;
my $g = GraphViz->new();
foreach (@commands) {
    my ( $command, @args ) = @$_;
    $g->$command( @args );
}