Override the visualchildrencount property and the getvisualchild in ironpython

I would convert the text below (c#) in IronPython.
I need create a DrawingVisual and I must override the VisualChildrenCount property and the GetVisualChild method.

source: official web Microsoft

// Provide a required override for the VisualChildrenCount property.
        protected override int VisualChildrenCount
        {
            get { return _children.Count; }
        }

        // Provide a required override for the GetVisualChild method.
        protected override Visual GetVisualChild(int index)
        {
            if (index < 0 || index >= _children.Count)
            {
                throw new ArgumentOutOfRangeException();
            }

            return _children[index];
        }

class MyVisualHost(FrameworkElement):

    def __init__(self, drawingVisual):

        self._children = VisualCollection(self)
        self._children.Add(drawingVisual)

        self.VisualChildrenCount = self._children.Count

        def GetVisualChild(self, index):
            try:
                if (index <= 0) or (index >= _children.Count):

                     System.ArgumentOutOfRangeException()

                else:
                    return _children[index]
            except:
                pass

myVisualHost = MyVisualHost(drawingVisual)

Message:Expected property for VisualChildrenCount, but found int.

Any suggestions?, thanks