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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 delete_attributes(self, attrs):
 """ Delete just these attributes, not the whole object. :param attrs: Attributes to save, as a list of string names :type attrs: list :return: self :rtype: :class:`boto.sdb.db.model.Model` """

        assert(isinstance(attrs, list)), "Argument must be a list of names of keys to delete."
        self._manager.domain.delete_attributes(self.id, attrs)
        self.reload()
        return self