[0] tag name
  [1] attribute hash reference
  [2] data
  [3] ...: one array ref for each nested tag

##</code><code>##

[ family => { name => 'Kawasaki' } => undef,
  [father => {} => 'Yasushisa' ],
  [mother => {} => 'Chizuko' ],
  [children => {} => undef,
    [girl => {} => 'Shiori'],
    [boy  => {} => 'Yasuke'],
    [boy  => {} => 'Kairi']
  ]
]