[問題] split syntax

[azulazure (獨在異鄉為異客)]

I'm writing a python script about "split" function,

trying to use space to split a string.

It should work the same way as the built-in split function.

For example, "This is a sentence" should have the output
['This', 'is', 'a', 'sentence']

This the is script I have so far, but it won't give me the last word
in the sentence. If anyone knows how to fix it, I'll appreciate it very much.

>>> word = ""
>>> output = []
>>> input = "This is a sentence"
>>> for x in input:
...     if x not in " ":
...             word = word + x
...     else:
...             output.append(word)
...             word = " "
...
>>> output
['This', ' is', ' a']


I guess it's because there's only three space between the words so I get this
output, but this the the closest I can get.

I have to admit that this is my homework, but I've been working on it for
three days. I hope I can get some feedback on it.

By the way, I just had one lesson on python. I don't know many of the commands
yet (as you can see from this simple script). I'd appreciate it if you can
use simple language to fix this script.

Sorry I have to type in English. I have no access to Chinese now.

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