ImportError: cannot import name AddTWoIntsResponse

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I am following a tutorial and where my srv file is AddTwoInts.srv

int64 a
int64 b
---
int64 sum

and i have created a server.py file under scripts

#!/usr/bin/env python

from __future__ import print_function

from service_node.srv import AddTwoInts,AddTWoIntsResponse

import rospy
def handle_add_two_inst(req):
    print("Returning [%s + %s = %s]"%(req.a, req.b, (req.a + req.b)))
    return AddTwoIntsResponse(req.a + req.b)
def add_two_ints_server():
    rospy.init_node('add_two_ints_server')
    s= rospy.Service('add_two_ints', AddTwoInts, handle_add_two_ints)
    print("Ready to add two ints.")
    rospy.spin()

if __name__ == "__main__":
    add_two_ints_server()

after made changes on cmake and package xml and runiing catkin_make

i tried to run the server.py using

rosrun service_node server.py

and i am getting the following error

Traceback (most recent call last):
  File "/home/akash/catkin_ws/src/service_node/scripts/server.py", line 5, in <module>
    from service_node.srv import AddTwoInts,AddTWoIntsResponse
ImportError: cannot import name AddTWoIntsResponse