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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 common(self):
 """ Return the set of parameters that are common to all types of keys. :return: Dictionary """

        res = {"kty": self.kty}
        if self.use:
            res["use"] = self.use
        if self.kid:
            res["kid"] = self.kid
        if self.alg:
            res["alg"] = self.alg
        return res