def print_models(unprinted_designs, completed_models):

"""

模拟打印每个设计，直到没有未打印的设计为止

打印每个设计后，都将其移到列表completed_models中

:param unprinted_designs: 没有打印的设计

:param completed_models: 已经完成打印的设计

:return:

"""

while unprinted_designs:

current_design = unprinted_designs.pop()

# 模拟根据设计制作3D打印模型的过程

print("Printing model: " + current_design)

completed_models.append(current_design)

def show_completed_models(completed_models):

""" 显示打印好的所有模型 """

print("\nThe following models have been printed:")

for completed_model in completed_models:

print(completed_model)

unprinted_designs = ['iphone case', 'robot pendant', 'dodecahedron']

completed_models = []

# 切片表示法[:]，获取副本数据

print_models(unprinted_designs[:], completed_models)

show_completed_models(completed_models)

print("\n")

print(unprinted_designs)

print("\n")

print_models(unprinted_designs, completed_models)

show_completed_models(completed_models)

print(unprinted_designs)