minimum cost spanning tree

Error : a bytes-like object is required, not 'str' : ['dot', '-Tsvg']

   digraph D {
      {rank=same 1}
      {rank=same 2 6}
      {rank=same 3 5}
      {rank=same 4}
      1 -> 2
      2 -> 3
      3 -> 4
      4 -> 5
      5 -> 6
      6 -> 1
    }