For reference, SeExpr is only used for a certain amount of scripting (usually around pattern generations etc). It's an industry standard in visual effects and animation workflows and was created by Disney;
http://wdas.github.io/SeExpr/
It is not used for general purpose scripting, for which Krita allows you to write Python scripts instead.
It is not used for general purpose scripting, for which Krita allows you to write Python scripts instead.