''' Purpose: function exploration with list manipulations
'''


def rotate( x ) :
    ''' Updates list x by moving the last element of list x (if any) to the
            beginning of list x (a circular shift)
        Returns None
    '''

    pass

def rotate_k_times( x, k ) :
    ''' Updates list x by performing k circular shifts
        Returns None
    '''

    pass

def common( x, y ) :
    ''' Returns a new list whose elements are those elements in x that are also in y.
        The function does not modify parameters x and y in any way.
    '''

    pass

if ( __name__ == '__main__' ):    # __name__ is a built in python variable.
    import abet                   #   it is set to __main__ if you are running
                                  #       that module as a program
                                  #   it is set to the name of the module
                                  #       if it is being imported

    abet.test_rotate()
    abet.test_rotate_k_times()
    abet.test_common()