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Editorial Team
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Asked: 2026-05-15T16:54:35+00:00

I am currently creating my deque object using the following, self.CommandList = deque(([‘S’, False,

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I am currently creating my deque object using the following,

self.CommandList = deque((['S', False, 60],['c'],['g16'],['i50'],['r30', True],['u320'],['o5000'],['b1'],['B4500'],['W1'],['l5154'],['!10'],['p2', True, 10],['e1'],['K20'],['U0'],['Y0']))

But I wish to add a similar list to the queue later but using appendleft, so it can jump ahead of the list. I assumed the following, but had no luck.

NewList = (['S'],['c'],['!10'],['p4'],['o1200'],['i50'],['r30'],['b10'],['d1'],['A', True, 163])
self.CommandList.appendleft(NewList)

Is this even possible with appendleft?

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1 Answer

  1. Editorial Team

    I think you want .extendleft here. This will “extend the list” instead of just appending the list as one element.

    z = collections.deque([1,2,3,4])   # [1, 2, 3, 4]

z.appendleft(['bad', 'news'])   # [ ['bad', 'news'], 1, 2, 3, 4 ]
z.extendleft(['good', 'news'])  # [ 'good', 'news', ['bad', 'news'], 1, 2, 3, 4 ]

    If they are getting inserted in reverse, the quick fix is to just reverse the list:

    z.extendleft(reversed(['good', 'news']))
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