code: def create(self, available_add_on_sid, accept_terms_of_service,
                 configuration=values.unset, unique_name=values.unset):
          
          data = values.of({
              'AvailableAddOnSid': available_add_on_sid,
              'AcceptTermsOfService': accept_terms_of_service,
              'Configuration': serialize.object(configuration),
              'UniqueName': unique_name,
          })
  
          payload = self._version.create(
              'POST',
              self._uri,
              data=data,
          )
  
          return InstalledAddOnInstance(self._version, payload, )
docs: Create a new InstalledAddOnInstance
  
          :param unicode available_add_on_sid: A string that uniquely identifies the Add-on to install
          :param bool accept_terms_of_service: A boolean reflecting your acceptance of the Terms of Service
          :param dict configuration: The JSON object representing the configuration
          :param unicode unique_name: The string that uniquely identifies this Add-on installation
  
          :returns: Newly created InstalledAddOnInstance
          :rtype: twilio.rest.preview.marketplace.installed_add_on.InstalledAddOnInstance