Does stuff with like, fields, and expressions, and stuff. Also things.
You need to turn on regexs in Painless if you want any of the field extraction stuff
./bin/elasticsearch -Escript.painless.regex.enabled=true
Also, you need to extract from the .keyword version of fields if you're using the defauld elasticsearch mapping as .exsplit() and .exregex() use doc[] and you can't access doc[] for analyzed fields.