Simple value returning function with odd or even test

return_test2.py

# Simple value returning function, plus odd or even test
# return_test2.py

def pass_info(x, y):
    sum = x + y
    # nested conditional testing if a new math operation changes the sum returned?
    # tests if sum is even
    if (sum % 2 == 0):
        sum += 1
    # tests if sum is odd
    elif (sum % 2 == 1):
        sum -= 1
    return sum

def main():
    output = pass_info(5, 4)
    print(output)

main()