Dot([String name = "Undefined", int n = -1]) {
    _name = name;
    num = n;
    _ln = <int, int>{};
  }
  Dot.fromTwoLists(String name, List<int> num0, List<int> length,
      [int n = -1]) {
    _name = name;
    num = n;
    Map<int, int> nw = <int, int>{};
    if (num0.length != length.length) {
      print("Error in lists");
    } else {
      for (var i = 0; i < num0.length; i++) {
        nw[num0[i]] = length[i];
        _ln = nw;
      }
    }
  }
  Dot.fromMap(String name, Map<int, int> l, [int n = -1]) {
    _name = name;
    num = n;
    _ln = l;
  }