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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_cat_dict(self, cat_dict_class, key_in_self, check_for_dupes=True, **kwargs):
 """Add a CatDict to this Entry if initialization succeeds and it doesn't already exist within the Entry. """

        # Try to create a new instance of this subclass of `CatDict`
        new_entry = self._init_cat_dict(cat_dict_class, key_in_self, **kwargs)
        if new_entry is None:
            return False

        # Compare this new entry with all previous entries to make sure is new
        if cat_dict_class != Error:
            for item in self.get(key_in_self, []):
                if new_entry.is_duplicate_of(item):
                    item.append_sources_from(new_entry)
                    # Return the entry in case we want to use any additional
                    # tags to augment the old entry
                    return new_entry

        self.setdefault(key_in_self, []).append(new_entry)

        return True