"""
 birthday_2.py

 Second version of happy birthday song.

 Printing only in main;
 the other testable "birthday" function has clean inputs and outputs.
"""

def birthday(name):
    return f"""Happy birthday to you,
happy birthday to you,
happy birthday dear {name},
happy birthday to you!"""

def main():
    song = birthday('Sally')
    print(song)

main()