Кэширование малых чисел в Python

>>> l = [1,2,3,1]
>>> l[0] == l[-1]
True
>>> l[0] is l[-1]
True

for number in number_list:
    if number is not number_list[-1]:
        print(number, end=', ')
    else:
        print(number, end='; ')

lst = [1, 4, 17, 1, 2, 3, 1]
 
with open('file.txt', 'w', encoding='utf-8') as fout:
    text = ', '.join(map(str, lst)) + ';'
    print(text, file=fout)

>>> x = 1000000000
>>> y = 1000000000
>>> id(x), id(y)
(3075303392, 3075303376)
>>> 
>>> x = 1000000
>>> y = 1000000
>>> id(x), id(y)
(3075303712, 3075303392)
>>> 
>>> x = 100
>>> y = 100
>>> id(x), id(y)
(136594864, 136594864)
>>>

lst = [1, 4, 17, 1, 2, 3, 1]
for number in lst:
    if number != lst[-1]:
        print(number, end=', ', file=tmb_data_out)
    else:
        print(number, end='; ', file=tmb_data_out)

lst = [1, 4, 17, 1, 2, 3, 1]
for number in lst:
    if number is not lst[-1]:
        print(number, end=', ', file=tmb_data_out)
    else:
        print(number, end='; ', file=tmb_data_out)

>>> lst = [1, 4, 17, 1, 2, 3, 1]
>>> length = len(lst)
>>> for i in range(length):
...     number = lst[i]
...     if i + 1 < length:
...         print(number, end=', ')
...     else:
...         print(number, end=';')
...         print()
... 
1, 4, 17, 1, 2, 3, 1;
>>>

>>> import copy
>>> first = [["11", "22", "33"]]
>>> second = copy.copy(first)
>>> second is first
False
>>> second[0] is first[0]
True