#!/usr/bin/python
import sys
betty_botter = 'Betty Botter bought a bit of butter But the bit of' \
                'butter Betty Botter bought was bitter So Betty ' \
                'Botter bought a better bit of butter '
expected_output = 'botter betty bought a bit of butter But the bit of'\
                    'butter botter betty bought was bitter So botter ' \
                     'betty bought a better bit of butter '
def botter_betty():
    global betty_botter
    
    
    betty_botter = betty_botter.replace('Botter', 'betty')
    betty_botter = betty_botter.replace('Betty', 'botter')
    
def main(args):
    botter_betty()
    assert betty_botter == expected_output, "Failed"
    print("Success")
    
if __name__ == '__main__':
    main(sys.argv)