python中如何使用函数改变list

def rotate(nums, k):
    length=len(nums)
    if length!=0:
        nums=nums[length-k:length]+nums[0:length-k]
 
l=[1,2,3,4,5,6,7]
rotate(l,3)
print(l)

def rotate(nums, k):
    length=len(nums)
    if length!=0:
        nums[:]=nums[length-k:length]+nums[0:length-k]
 
l=[1,2,3,4,5,6,7]
rotate(l,3)
print(l)

>>> test = list()
>>> test
[]

>>> test = list('cat')
>>> test
['c', 'a', 't']

>>> a_tuple = ('I love Python.', 'I also love HTML.')
>>> test = list(a_tuple)
>>> test
['I love Python.', 'I also love HTML.']

>>> a_dict = {'China':'Beijing', 'Russia':'Moscow'}
>>> test = list(a_dict)
>>> test
['China', 'Russia']

>>> a_set = {1, 4, 'sdf'}
>>> test = list(a_set)
>>> test
[1, 'sdf', 4]

>>> test1 = list(range(10))
>>> test2 = list(map(int, [23.2, 33.1]))
>>> test1
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> test2
[23, 33]

if __name__ == '__main__':
    source_list = ["a", "b", "c", "d"]
    new_list1 = list(source_list)
    print(id(source_list), id(new_list1))
    # output: 4313597760 4312890304
 
    new_list2 = source_list
    print(new_list1)
    # output: ['a', 'b', 'c', 'd']
    print(new_list2)
    # output: ['a', 'b', 'c', 'd']
 
    source_list[0] = "e"
    print(new_list1)
    # output: ['a', 'b', 'c', 'd']
    print(new_list2)
    # output: ['e', 'b', 'c', 'd']