How to add upi payment gateway using python

I want to add upi payment option in my website in which Website gives a UPI id and tell user to send x amount of money to that VPA after that user enter the 12 digit reference number and click on add money. Then my site check if x amount of money recieved in given vpa then add x amount of money in user’s account else say sorry transaction could not verified. How can i do this in python flask with paytm(not business api) or any upi app