How to access the operating system of your device using python

import os

a=input("Enter the name of the file you wish to open")

c=os.startfile(a)

print("opening",a)

b=input("Do you wish to do it again(Y/N)-->")

if(b.lower()=="y"):

    d=input("Enter the name of the file you wish to open")

    e=os.startfile(d)

    print("opening",d)

    f=input("Do you wish to do it again(Y/N)-->")

elif(b.lower()=="n"):

    print("Operation Ended")

else:

    print("Invalid Input")