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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 _searchable_form(self) -> 'Language': """ Convert a parsed language tag so that the information it contains is in the best form for looking up information in the CLDR. """

        if self._searchable is not None:
            return self._searchable

        self._searchable = self._filter_attributes(
            {'language', 'script', 'region'}
        ).simplify_script().prefer_macrolanguage()
        return self._searchable