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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 append_with(self, obj, **properties):
        '''Add an item to the dictionary with the given metadata properties'''
        for prop, val in properties.items():
            val = self.serialize(val)
            self._meta.setdefault(prop, {}).setdefault(val, []).append(obj)
        self.append(obj)