{
  a =>
    '5'
  b =>
    '4'
  d =>
    '1'
  top =>
    {
      a =>
        '7'
      b =>
        '4'
      bottom =>
        {
          b =>
            '4'
          c =>
            '9'
          d =>
            '3'
        }
      c =>
        '2'
      top =>
        {
          a =>
            '5'
          b =>
            '4'
          c =>
            '9'
          top =>
            {
              a =>
                '5'
              b =>
                '6'
              bottom =>
                {
                  b =>
                    '6'
                  c =>
                    '7'
                }
              c =>
                '9'
            }
        }
    }
}