字典dict
fromkeys函数：
# new_dict = dict.fromkeys(keys, default_value)
# case1
keys = ['name', 'age', 'city']
default_value = 'Unknown'
new_dict = dict.fromkeys(keys, default_value)
print(new_dict)
# case2
keys = ['name', 'age', 'city']
default_values = ['John Doe', 30, 'New York']
new_dict = dict.fromkeys(keys, default_values)
print(new_dict)
# case3
keys = ['name', 'age', 'city']
new_dict = dict.fromkeys(keys)
print(new_dict)