def IndexLstToIndexStr(index):
    """
    IndexLstToIndexStr
    ==================
    transform a list into an index element
    e.g. list named 'a' and index ref is [1,1,2], result is
    '[1][1][2]'
 
    @param index: a flat list of indexes
    
    @return: a string
 
    """ 
    return str(index).replace(',','][')