做 google 联系人的自动化练习，新建了一个子类，继承了 appium 中的 Webdriver，运行后提示继承的类无 session_id 属性，求解答
1.继承类代码，在 uiTest.py 文件中，只贴出了跟本题有关的方法：

from appium import webdriver
from appium.webdriver.webdriver import WebDriver
import logging
import configparser
import os
import time
class myui(WebDriver):
    """继承appium的Webdriver类，封装一些自己的方法"""
    def __init__(self,appPackage,appActivity):
        """初始化连接数据"""
        self.desired_caps = {}
        self.driver = None
        self.desired_caps = {
            'platformName': 'android',
            'platformVersion': '9',
            'deviceName': 'GM9',
            'automationName': 'uiautomator2'
        }
        self.desired_caps['appPackage'] = appPackage
        self.desired_caps['appActivity'] = appActivity

    def connect_driver(self,hostName='http://127.0.0.1:4723/wd/hub'):
        """连接appium服务器，hostname默认为本机的服务器"""
        try:
            self.driver = webdriver.Remote(hostName, self.desired_caps)
            print(type(self.driver))
            self.driver.implicitly_wait(5)
            logging.info('driver_connect success')
        except Exception as myerror:
            logging.error('connect error',myerror)

    def findElement(self,type,element):
        #能过传入type寻找类型,elment控件字串，自动查找控件，返回控件，如未找到则返回None
        e = None
        try:
            if type=='id':
                e = self.driver.find_element_by_id(element)
            elif type=='class':
                e = self.driver.find_elements_by_class_name(element)
        except Exception as er:
            logging.error('finderror:',er)
            self.getScrren()
            assert False
        return e

2.运行代码：

from time import sleep
from MTBFTest.uiTest import myui
import pytest
import logging
import mylog
import os

class TestCase_contact():

    def test_newConteact(self):
        try:
            conf = myui.getDate('contactconfig.ini')
            driver = myui(conf.get('apppackage'),conf.get('appactivity'))
            driver.connect_driver()
            driver.findElement('id',conf.get('skip_id')).click()
            sleep(3)
           driver.tap([(946,1884)],500)     #这一行代码报错
            #driver.find_element_by_xpath('//*[@content-dest="创建联系人"]')
            ine = driver.findElement('id',conf.get('in_name_f_id'))
            conteactName = ine.find_elements_by_class_name(conf.get('in_classes'))
            conteactName[0].send_keys('test')
            conteactName[1].send_keys('test')
            driver.find_element_by_id(conf.get('save_id')).click()
            e = driver.find_element_by_xpath("//*[contains(@text,'已保存')]")  # 此处为使用xpath模糊定位定位toast
            text = e.get_attribute("text")
            logging.info(text)
            assert '已保存' in text
            ui.press_keycode(4)
        except Exception as e:
            logging.error(e)
            assert False
        finally:
            driver.driverquit()
if __name__=='__main__':
    mylog.startLog()
    pytest.main(['-q'])

3.运行结果：

4.错误提示为： AttributeError: 'myui' object has no attribute 'session_id'