Comment 1 for bug 1976220

As described in [1], best_match and lookup behave differently and are not replaceable directly. This difference might affect users, and thus leaving the current code is a better choice.

[1] https://docs.pylonsproject.org/projects/webob/en/stable/api/webob.html#webob.acceptparse.AcceptLanguageValidHeader.best_match

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In [29]: from webob import Request

In [30]: req = Request.blank('/test?check=a&check=b&name=Bob')

In [31]: req.accept_language = 'en-gb;q=1, en;q=0.8'

In [32]: all_languages = ['en_US']

In [33]: req.accept_language.best_match(all_languages)
Out[33]: 'en_US'

In [35]: req.accept_language.lookup(all_languages, default='ja_JP')
Out[35]: 'ja_JP'