ksp

You get Sublime Text from https://www.sublimetext.com/

Note: you can use it without any restrictions but you still need to buy a license. It’s really worth it!

Thx to Nils Liberg and nojanath who created a KSP plugin for Sublime Text with many new possibilities like macros, for statements, functions and many more, using Sublime is almost essential when it comes to complex scripts since it simplifies things a lot (like structuring our code and saving lots of code-lines). It also helps us to better reveal some errors. There are also new practices & features, like a different (easier) coding with less required code. Read more »

ksp

this article explains everything about advanced user defined functions in sublime text. The basic syntax, how to use them with mixed arguments, how to declare local variables and how to return values.
It also shows the differences between classic and advanced functions.
Read more »