(name => 'array ref to self',
 code => '@a= (1,\@a,3);
          GraphViz::Data::Structure->new(\@a,%title%)->graph->as_canon',
)
%%
(name => 'scalar ref to array element',
 code => '@a=(1,2,3); 
          $a=\$a[2];
          GraphViz::Data::Structure->new($a,%title%)->graph->as_canon',
)
%%
(name => 'hash ref to self',
 code => '%refhash=(Self=>\%refhash);
          GraphViz::Data::Structure->new(\%refhash,%title%)->graph->as_canon',
 )
%%
(name => 'scalar ref to hash element',
 code => '%refhash=(One=>1,Two=>2);
          $a=\$refhash{One};
          GraphViz::Data::Structure->new($a,%title%)->graph->as_canon',
)
%%
(name => 'complex case',
 code => '@a=(1,2); 
          $a[0]=\@a; 
          $a[1]=\$a[0]; 
          GraphViz::Data::Structure->new(\@a,%title%)->graph->as_canon',
 )