How to use the uiautomator2.session.Selector function in uiautomator2

def drag_to(self, *args, **kwargs):
        duration = kwargs.pop('duration', 0.5)
        timeout = kwargs.pop('timeout', None)
        self.must_wait(timeout=timeout)

        steps = int(duration * 200)
        if len(args) >= 2 or "x" in kwargs or "y" in kwargs:

            def drag2xy(x, y):
                x, y = self.session.pos_rel2abs(x,
                                                y)  # convert percent position
                return self.jsonrpc.dragTo(self.selector, x, y, steps)

            return drag2xy(*args, **kwargs)
        return self.jsonrpc.dragTo(self.selector, Selector(**kwargs), steps)

def child(self, **kwargs):
        self[self.__childOrSibling].append("child")
        self[self.__childOrSiblingSelector].append(Selector(**kwargs))
        return self

def child_by_description(self, txt, **kwargs):
        # need test
        if "allow_scroll_search" in kwargs:
            allow_scroll_search = kwargs.pop("allow_scroll_search")
            name = self.jsonrpc.childByDescription(self.selector,
                                                   Selector(**kwargs), txt,
                                                   allow_scroll_search)
        else:
            name = self.jsonrpc.childByDescription(self.selector,
                                                   Selector(**kwargs), txt)
        return UiObject(self.session, name)

def child_by_instance(self, inst, **kwargs):
        # need test
        return UiObject(
            self.session,
            self.jsonrpc.childByInstance(self.selector, Selector(**kwargs),
                                         inst))

def __call__(self, steps=20, max_swipes=500, **kwargs):
                if self.action in ["forward", "backward"]:
                    method = jsonrpc.scrollForward if self.action == "forward" else jsonrpc.scrollBackward
                    return method(selector, self.vertical, steps)
                elif self.action == "toBeginning":
                    return jsonrpc.scrollToBeginning(selector, self.vertical,
                                                     max_swipes, steps)
                elif self.action == "toEnd":
                    return jsonrpc.scrollToEnd(selector, self.vertical,
                                               max_swipes, steps)
                elif self.action == "to":
                    return jsonrpc.scrollTo(selector, Selector(**kwargs),
                                            self.vertical)