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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 defnoun(self, singular, plural):
 """ Set the noun plural of singular to plural. """

        self.checkpat(singular)
        self.checkpatplural(plural)
        self.pl_sb_user_defined.extend((singular, plural))
        self.si_sb_user_defined.extend((plural, singular))
        return 1