# Error with base/generic function calls

**URL:** <https://discourse.julialang.org/t/error-with-base-generic-function-calls/44174>\
**Category:** General Usage\
**Created:** [August 3, 2020, 7:36am UTC](https://discourse.julialang.org/t/error-with-base-generic-function-calls/44174 "2020-08-03T07:36:41Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![ConnectedSystems](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/connectedsystems/32/16815_2.png) [@ConnectedSystems](https://discourse.julialang.org/u/ConnectedSystems)\
**Post date:** [August 3, 2020, 10:22am UTC](https://discourse.julialang.org/t/error-with-base-generic-function-calls/44174/3 "2020-08-03T10:22:26Z")

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@oheil thanks for your response

Now that you’ve explained where it was moved, I found [this post](https://discourse.julialang.org/t/why-has-subtypes-function-been-moved-to-module-interactiveutils-v0-7-0/11975/6) which made me think about what might be the Julian way of doing what I wanted.

In my case it was simple enough to re-conceptualize so that the following was suitable:

```nohighlight
a isa CustomType
# true

# the above also works for subtypes of CustomType

```

So my direct issue is solved but I’m kind of annoyed that the documentation, with example, didn’t explicitly mention this ([Reflection and introspection · The Julia Language](https://docs.julialang.org/en/v1/devdocs/reflection/#Subtypes-1)). I feel the info is buried.

But anyway, thanks again.

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