# Seems to be old code in Codercise I.13.4

**URL:** <https://discuss.pennylane.ai/t/seems-to-be-old-code-in-codercise-i-13-4/8922>\
**Category:** Codebook\
**Created:** [August 18, 2025, 11:28pm UTC](https://discuss.pennylane.ai/t/seems-to-be-old-code-in-codercise-i-13-4/8922 "2025-08-18T23:28:54Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![PranavUpreti](https://avatars.discourse-cdn.com/v4/letter/p/aeb1de/32.png) [@PranavUpreti](https://discuss.pennylane.ai/u/PranavUpreti)\
**Post date:** [August 18, 2025, 11:28pm UTC](https://discuss.pennylane.ai/t/seems-to-be-old-code-in-codercise-i-13-4/8922/1 "2025-08-18T23:28:54Z")

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Hi there! Hope you’re doing well.

It seems like the explanation preceding Codercise I.13.4 may contain old code.

It says to use `'qml.MultiControlledX(control_wires=[0, 1, 2], wires=4, control_values="001")``

but this gave me an error: `Error: MultiControlledX. __init__ () got an unexpected keyword argument 'control_wires'.`

Using `qml.MultiControlledX(wires=[0, 1, 2, 3], control_values=[0, 0, 1])` works.

Thanks!

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**Author:** ![daniela.murcillo](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/daniela.murcillo/32/3612_2.png) [@daniela.murcillo](https://discuss.pennylane.ai/u/daniela.murcillo)\
**Post date:** [August 19, 2025, 1:39pm UTC](https://discuss.pennylane.ai/t/seems-to-be-old-code-in-codercise-i-13-4/8922/2 "2025-08-19T13:39:28Z")

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Hi @PranavUpreti! Welcome to the forum.  
Yes, you are definitely right about this. Thank you for reporting this.  
I’ll correct it asap.

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**Author:** ![Mulldrifter](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/mulldrifter/32/4209_2.png) [@Mulldrifter](https://discuss.pennylane.ai/u/Mulldrifter)\
**Post date:** [February 1, 2026, 7:25am UTC](https://discuss.pennylane.ai/t/seems-to-be-old-code-in-codercise-i-13-4/8922/3 "2026-02-01T07:25:11Z")

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Hello @daniela.murcillo ,

The same problem also appears in the tip of the codercise G.3.1

> _Tip._ `MultiControlledX(control_wires, wires, control_values)` has a specified set of `control_wires`, a single target wire given by `wires`, and a string of control values, e.g., `control_values = "1011"` rather than a list of bits `[1,0,1,1]`.

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<div class="post-metadata">

**Author:** ![daniela.murcillo](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/daniela.murcillo/32/3612_2.png) [@daniela.murcillo](https://discuss.pennylane.ai/u/daniela.murcillo)\
**Post date:** [February 3, 2026, 3:53pm UTC](https://discuss.pennylane.ai/t/seems-to-be-old-code-in-codercise-i-13-4/8922/4 "2026-02-03T15:53:00Z")

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Hi @Mulldrifter, welcome to the forum!  
Thanks for reporting this, I’ll fix it right now.