Describing pre-exercise code

I loaded some packages and created some variables in the pre-exercise code. How do I tell students that I've done this?

Add a sentence at the end of the exercise's introductory text (Context block). For example, you could say
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​pandas  is loaded, and the Titanic  dataset is available in your workspace.

You can also mention the existence of any variables in the Sample Code. For example,

If you created many variables, it could be easier to list them. In R, use ls.str() ; in Python use %who .

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