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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 add_photometry(self, compare_to_existing=True, **kwargs):
 """Add a `Photometry` instance to this entry."""

        self._add_cat_dict(
            Photometry,
            self._KEYS.PHOTOMETRY,
            compare_to_existing=compare_to_existing,
            **kwargs)
        return