# Error in Codercises V2.2.a

**URL:** <https://discuss.pennylane.ai/t/error-in-codercises-v2-2-a/7616>\
**Category:** Codebook\
**Created:** [November 21, 2024, 2:25pm UTC](https://discuss.pennylane.ai/t/error-in-codercises-v2-2-a/7616 "2024-11-21T14:25:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![quantumel](https://avatars.discourse-cdn.com/v4/letter/q/7ea924/32.png) [@quantumel](https://discuss.pennylane.ai/u/quantumel)\
**Post date:** [November 21, 2024, 2:25pm UTC](https://discuss.pennylane.ai/t/error-in-codercises-v2-2-a/7616/1 "2024-11-21T14:25:20Z")

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Hi,

There is an error in the instruction in the original code:

# Define the single and double excitations

singles, doubles = **qchem.excitations** (electrons=2, orbitals=qubits)

With this code you got this error:  
**Error: name ‘qchem’ is not defined.**

Correction:  
singles, doubles = **qml.qchem.excitations** (electrons=2, orbitals=qubits)

 ![error-qml.qchem-codecise-V2.2.a](https://canada1.discourse-cdn.com/flex012/uploads/pennylane/original/2X/6/615cbdefa045d72bbbc2812917dae09b22a3f062.jpeg)

Best Regards

---

<div class="post-metadata">

**Author:** ![CatalinaAlbornoz](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/catalinaalbornoz/32/1196_2.png) [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\
**Post date:** [November 21, 2024, 4:30pm UTC](https://discuss.pennylane.ai/t/error-in-codercises-v2-2-a/7616/2 "2024-11-21T16:30:33Z")

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Hi @quantumel ,

Thank you for pointing this out!

We’ll make sure to fix it in the Codebook.

Thanks for helping us make it better!