working GstVideo.VideoFilter in Python

class TestFilter(GstVideo.VideoFilter):
    __gstmetadata__ = (
        "TestFilter plugin",
        "test_filter.py",
        "Description",
        "Contact"
    )

    _srctemplate = Gst.PadTemplate.new(
        'src',
        Gst.PadDirection.SRC,
        Gst.PadPresence.ALWAYS,
        Gst.caps_from_string('video/x-raw, format=(string){ YV12, AYUV, YUY2, UYVY }')
    )

    _sinktemplate = Gst.PadTemplate.new(
        'sink',
        Gst.PadDirection.SINK,
        Gst.PadPresence.ALWAYS,
        Gst.caps_from_string('video/x-raw, format=(string){ YV12, AYUV, YUY2, UYVY }')
    )

    __gsttemplates__ = (_sinktemplate, _srctemplate)

    def __init__(self):
        GstVideo.VideoFilter.__init__(self)
        self.set_passthrough(True)

    def do_transform_frame_ip(self, frame):
        print(frame.buffer.pts)
        return Gst.FlowReturn.OK