# How to make changes/develop a package in the StdLib?

**URL:** <https://discourse.julialang.org/t/how-to-make-changes-develop-a-package-in-the-stdlib/88906>\
**Category:** Package Management\
**Created:** [October 18, 2022, 11:34am UTC](https://discourse.julialang.org/t/how-to-make-changes-develop-a-package-in-the-stdlib/88906 "2022-10-18T11:34:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![habemus-papadum](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/habemus-papadum/32/4086_2.png) [@habemus-papadum](https://discourse.julialang.org/u/habemus-papadum)\
**Post date:** [October 18, 2022, 11:34am UTC](https://discourse.julialang.org/t/how-to-make-changes-develop-a-package-in-the-stdlib/88906/1 "2022-10-18T11:34:05Z")

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Hello, I want to add function to `Downloads.jl` (to allow overriding the default Downloader). `Downloads.jl` is in the stdlib/default sysimage, and I am not sure what the best development flow is for making changes and testing. Do I need to build julia from scratch to make changes to `Downloads.jl`? I have tried using `] dev Downloads.jl` in a clean environment using default sysimage and that does not seem to work. – adding a function a restarting julia has no effect.

Thank you, Nehal

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**Author:** ![ericphanson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ericphanson/32/215186_2.png) [@ericphanson](https://discourse.julialang.org/u/ericphanson)\
**Post date:** [October 18, 2022, 11:43am UTC](https://discourse.julialang.org/t/how-to-make-changes-develop-a-package-in-the-stdlib/88906/2 "2022-10-18T11:43:24Z")

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The quick way is to change the UUID temporarily, so that Julia sees it as a separate package from the baked-in version. See [https://github.com/JuliaLang/Pkg.jl#using-the-development-version-of-pkgjl](https://github.com/JuliaLang/Pkg.jl#using-the-development-version-of-pkgjl) for how to do that (that’s for Pkg.jl, but it’s the same process for any stdlib pretty much).

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**Author:** ![habemus-papadum](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/habemus-papadum/32/4086_2.png) [@habemus-papadum](https://discourse.julialang.org/u/habemus-papadum)\
**Post date:** [October 18, 2022, 11:58am UTC](https://discourse.julialang.org/t/how-to-make-changes-develop-a-package-in-the-stdlib/88906/3 "2022-10-18T11:58:17Z")

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Thank you very much – instructions were easy to follow and was able to get it to work.