code: def getExtensionArgs(self):
          
          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
docs: 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}