why i have the output of [None, None, None]

[Skip Montanaro]

The print function in Python 3 returns None. The "ok" output is a side
effect. The actual value of evaluating that list comprehension is a
list of three None values.

Skip

On Thu, Apr 10, 2014 at 8:54 AM, length power <elearn2014 at gmail.com> wrote:
>>>> x=['','x1','x2','x3','   ']
>>>> x
> ['', 'x1', 'x2', 'x3', '   ']
>>>> [print("ok") for it in x if it.strip() !=""]
> ok
> ok
> ok
> [None, None, None]
>
> i understand there are three 'ok' in the output,but why i have the output of
> [None, None, None]
>
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