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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 forum_topic_get_by_tag_for_user(self, tag=None, author=None):
 """Get all forum topics with a specific tag"""


        if not tag:
            return None

        if author:
            r = self._request('ebuio/forum/search/bytag/' + tag + '?u=' + author)
        else:
            r = self._request('ebuio/forum/search/bytag/' + tag)
        if not r:
            return None

        retour = []

        for data in r.json().get('data', []):
            retour.append(data)

        return retour