Beginner - Not getting output in my textbook : I'm a student and have a question. I'm not getting the correct output in our textbook.

    first = 'I'
    second = 'love'
    third = 'Python'
    sentence = first + '' + second + '' + third + '.'

Output:

    I love Python. 

When I run it, nothing happens. Can someone explain why? Thanks in advance!