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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 authors(self, *usernames):
 """ Return the entries written by the given usernames When multiple tags are provided, they operate as "OR" query. """

        if len(usernames) == 1:
            return self.filter(**{"author__{}".format(User.USERNAME_FIELD): usernames[0]})
        else:
            return self.filter(**{"author__{}__in".format(User.USERNAME_FIELD): usernames})