def d( cities,a, b ) :
    ''' Returns the length of the edge between city a and city b
    '''
    
    pass
    
def swap( tour, i1, i2 ) :
    ''' Swaps the values of the tour elements at indices i1 and i2
    '''

    pass

def cost( cities, tour ) :
    ''' Returns the length traveled visiting all cities in the order
        indicated by tour. That length includes the length of the
        connection from the last city back to the first city.
    '''
    
    pass

if ( __name__ == "__main__" ) :
    import test_support

    test_support.test_d()
    test_support.test_swap()
    test_support.test_cost()