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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 getExtensionArgs(self):
 """Get a dictionary of unqualified simple registration arguments representing this request. This method is essentially the inverse of C{L{parseExtensionArgs}}. This method serializes the simple registration request fields. @rtype: {str:str} """

        args = {}

        if self.required:
            args['required'] = ','.join(self.required)

        if self.optional:
            args['optional'] = ','.join(self.optional)

        if self.policy_url:
            args['policy_url'] = self.policy_url

        return args