#!/usr/bin/perl

use strict;
use warnings;

use GraphViz;

my $g = GraphViz->new();

my $switches = {
   'switch0' => ['switch1', 'switch2', 'switch3'],
   'switch1' => ['switch4'],
};

for my $k (keys %$switches) {
   $g->add_edge($k => $_) for @{$switches->{$k}};
}

print $g->as_text;