from metaflow import FlowSpec, step, Parameter

class ExtraParam():
    extra = Parameter('extra',
                      required=True,
                      help="this is an extra parameter")

class ExtraParamFlow(ExtraParam, FlowSpec):

    myparam = Parameter('myparam', default=5)

    @step
    def start(self):
        print('myparam', self.myparam)
        print('extra', self.extra)
        self.next(self.end)

    @step
    def end(self):
        pass

if __name__ == '__main__':
    ExtraParamFlow()