Reverse list items in a stupid way

[pyth0n123]

Why is the following code not working?

text="I am very busy today"
a=text.split()
word=a
print(word)
word[4]=a[0]
word[3]=a[1]
word[2]=a[2]
word[1]=a[3]
word[0]=a[4]
print(word)

I get this answer which is wrong:
['I', 'am', 'very', 'busy', 'today']
['I', 'am', 'very', 'am', 'I']

I know I can do it easily with the following but I really want to know why the above code failed:

text="I am very busy today"
a=text.split()
a[::-1]

Thanks for your help.

[ichabod801]

Lists are mutable, and are therefore copied and passed by reference. 'a' is not a list, it is a pointer to a list. word = a copies the pointer not the list. So everything you do to word you do to a, and vice versa. You need to copy the list pointed to by a, with something like word = a[:]. Or just make a new list, word = [''] * len(a), since you are overwriting everything in word anyway.

[pyth0n123]

I wasn't aware of the pointer to a list thing. Thanks for the explanation.

[ThomasL]

This is a nice information video on youtube

[pyth0n123]

This is a nice information video on youtube

Thanks for the link but what he explained is not applicable to my scenario.