operator* multiplies the same reference



In [1]:

    
l = [[]] * 3
l[0] is l[1], l[0] is l[2]









    Out[1]:





(True, True)



In [2]:

    
l[0].append("abc")
l









    Out[2]:





[['abc'], ['abc'], ['abc']]



In [3]:

    
l = [1] * 3
print(l)
l[0] is l[1], l[0] is l[2]









    



[1, 1, 1]






    Out[3]:





(True, True)

Integers are immutable.



In [4]:

    
l[1] = 2
print(l)
l[0] is l[1], l[0] is l[2], l[1] is l[2]









    



[1, 2, 1]






    Out[4]:





(False, True, False)



In [5]:

    
l[2] = 2
print(l)
l[0] is l[1], l[0] is l[2], l[1] is l[2]









    



[1, 2, 2]






    Out[5]:





(False, False, True)



In [6]:

    
for i in range(-10, 260):
    x = i
    y = i + 1 - 1
    if x is not y:
        print(i)



In [7]:

    
l = [[] for _ in range(3)]
l









    Out[7]:





[[], [], []]



In [8]:

    
l[0].append("abc")
l









    Out[8]:





[['abc'], [], []]