def subscribe(self, on_next, on_err, on_compl):
    try:
        self.res.get()
        on_next(self.res.value)
    except Exception as ex:
        on_err(ex.args)
    on_compl()
def subscribe(self, on_next, on_err, on_compl):
    try:
        self.res.get()
        on_next(self.res.value)
    except Exception as ex:
        on_err(ex.args)
    on_compl()