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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 save(self, png_file):
 """Save png to disk. Parameters png_file : path to file file to write to Notes ----- It relies on _repr_png_, so fix issues there. """

        with open(png_file, 'wb') as f:
            f.write(self._repr_png_())