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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _convert(self, image, output=None):
 """Private method for converting a single PNG image to a PDF."""

        with Image.open(image) as im:
            width, height = im.size

            co = CanvasObjects()
            co.add(CanvasImg(image, 1.0, w=width, h=height))

            return WatermarkDraw(co, tempdir=self.tempdir, pagesize=(width, height)).write(output)