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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 _reduce_opacity(self):
 """ Reduce opacity for watermark image. """

        if self.image.mode != 'RGBA':
            image = self.image.convert('RGBA')
        else:
            image = self.image.copy()

        alpha = image.split()[3]
        alpha = ImageEnhance.Brightness(alpha).enhance(self.opacity)
        image.putalpha(alpha)

        self.image = image