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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def do_list():
 """ CLI action "list configurations". """

    dirs =  os.walk(CONFIG_ROOT).next()[1]
    if dirs:
        print "List of available configurations:\n"
        for d in dirs:
            print "  * {}".format(d)
    else:
        print "No configurations available."