def add(a,b):
# calculating the sum
    sum=a+b
    #opening the file in an append mode
    file = open('output.txt',"a")
    file.write(f'Sum of {a} and {b} is {sum}\n')
    #at last i close the file
    file.close()


#call the function
add(5,7)
add(2,6)