# define the shut_down function
def shut_down(s):
    if s == 'yes':
        return 'Shutting down'
    elif s == 'no':
        return 'Shutdown aborted'
    else:
        return 'Sorry'

# testing
print shut_down('yes') # will return 'Shutting down'
print shut_down('no') # will return 'Shutdown aborted'
print shut_down('foo') # will return 'Sorry'