# Pluto "custom cell"

**URL:** <https://discourse.julialang.org/t/pluto-custom-cell/132224>\
**Category:** General Usage\
**Created:** [September 9, 2025, 10:15am UTC](https://discourse.julialang.org/t/pluto-custom-cell/132224 "2025-09-09T10:15:07Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![Mikhail\_Kagalenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mikhail_kagalenko/32/13257_2.png) [@Mikhail\_Kagalenko](https://discourse.julialang.org/u/Mikhail_Kagalenko)\
**Post date:** [September 18, 2025, 3:01pm UTC](https://discourse.julialang.org/t/pluto-custom-cell/132224/10 "2025-09-18T15:01:21Z")

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> [@fonsp](#):
>
> The low-tech solution is to track calls to the function: (if you wrote it yourself)

I don’t write it myself. There’s a sequence of assignments, where a student writes a simple function, then uses it to write a slightly more complex function. The name of a function is fixed,  
so checking for its presence in an expression tree should not be hard.

> You could ask: “is there a way to use Julia’s introspection tools to check whether a function  
> `a` uses a function `b` in its definition?”

[That’s a good idea](https://discourse.julialang.org/t/introspection-for-checking-an-implementation/132495)

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