1. override
String debugDescribeChildren(String prefix)

Returns a description of this layer's children for use by toStringDeep.

Source 

@override
String debugDescribeChildren(String prefix) {
  String result = '$prefix \u2502\n';
  if (_firstChild != null) {
    Layer child = _firstChild;
    int count = 1;
    while (child != _lastChild) {
      result += '${child.toStringDeep("$prefix \u251C\u2500child $count: ", "$prefix \u2502")}';
      count += 1;
      child = child._nextSibling;
    }
    if (child != null) {
      assert(child == _lastChild);
      result += '${child.toStringDeep("$prefix \u2514\u2500child $count: ", "$prefix  ")}';
    }
  }
  return result;
}