Python-ネストリストアプリケーション(未完)

lists = ["m1", 1900, ["m2", 2000, ["m3", 2100]]]
for item_outer in lists:
    if isinstance(item_outer, list):
        for item_medium in item_outer:
            if isinstance(item_medium, list):
                for item_inner in item_medium:
                    print(item_inner)
            else:
                print(item_medium)
    else:
        print(item_outer)

def traverse_list(alist):
    for each_item in alist:
        if isinstance(each_item, list):
            traverse_list(each_item)
        else:
            print(each_item)

lists = ["m1", 1900, ["m2", 2000, ["m3", 2100]]]
traverse_list(lists)