https://github.com/onerobotics/vim-karel/blob/master/syntax/karel.vim
http://www.onerobotics.com/posts/2013/introduction-to-karel-programming/
https://code.visualstudio.com/docs/extensions/yocode#_new-language-support
https://code.visualstudio.com/docs/extensionAPI/language-support
https://manual.macromates.com/en/language_grammars
https://raw.githubusercontent.com/martinring/tmlanguage/master/tmlanguage.json
https://github.com/kkos/oniguruma/blob/master/doc/RE
https://docs.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-language-quick-reference
Now that we have our matches, we need our colors. The color associated with a match is specified by the name attribute. The color value of this name is defined by the current theme used by VS Code. Therefore, to consult all the available colors, you can open a default theme JSON file. It is located under the installation folder of VS Code (on windows, under AppData). For example, you can search for dark_vs.json, which is located under app/extensions/defaults/themes/. Therefore, it is not possible to create custom colors names for your language, unless you also create a custom theme for it.