# How to step into the function which defines \[ \]?

**URL:** <https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135>\
**Category:** New to Julia\
**Created:** [February 16, 2017, 2:21pm UTC](https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135 "2017-02-16T14:21:17Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![chobbes](https://avatars.discourse-cdn.com/v4/letter/c/848f3c/32.png) [@chobbes](https://discourse.julialang.org/u/chobbes)\
**Post date:** [February 16, 2017, 2:21pm UTC](https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135/1 "2017-02-16T14:21:17Z")

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I’m trying to take a look of the function which defines the syntax of the square brackets and the semi-colon. Apparently, I’m doing something very wrong:

```julia
julia> @enter [1;2]
ERROR: AssertionError: isa(arg,Expr) && arg.head == :call

```

Can anyone let me know what is the correct way to enter the right piece of the code? Thanks!

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**Author:** ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)\
**Post date:** [February 16, 2017, 2:27pm UTC](https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135/2 "2017-02-16T14:27:09Z")

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Does @enter temp = [1,2] work?

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**Author:** ![chobbes](https://avatars.discourse-cdn.com/v4/letter/c/848f3c/32.png) [@chobbes](https://discourse.julialang.org/u/chobbes)\
**Post date:** [February 16, 2017, 2:30pm UTC](https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135/3 "2017-02-16T14:30:19Z")

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Unfortunately not:

```julia
julia> @enter temp = [1;2]
ERROR: AssertionError: isa(arg,Expr) && arg.head == :call

julia> @enter temp = [1,2]
ERROR: AssertionError: isa(arg,Expr) && arg.head == :call

```

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**Author:** ![TsurHerman](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tsurherman/32/1234_2.png) [@TsurHerman](https://discourse.julialang.org/u/TsurHerman)\
**Post date:** [February 16, 2017, 2:35pm UTC](https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135/4 "2017-02-16T14:35:39Z")

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This might help:

```julia
using Gallium
f(x) = [x,x+1]
@enter f(1)

```

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**Author:** ![chobbes](https://avatars.discourse-cdn.com/v4/letter/c/848f3c/32.png) [@chobbes](https://discourse.julialang.org/u/chobbes)\
**Post date:** [February 16, 2017, 2:38pm UTC](https://discourse.julialang.org/t/how-to-step-into-the-function-which-defines/2135/5 "2017-02-16T14:38:05Z")

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Aha! Brilliant idea! Thanks for the workaround. It works!