Suffix -ist-.
The suffix "-ist-" denotes one who occupies himself with or devotes
himself to any special thing, as a business or a hobby, as "jugxi", to
judge, "jugxisto", a judge; "servi", to serve, "servisto", a servant;
"kuraci", to treat (as a doctor), "kuracisto", a doctor; "lavi", to
wash, "lavisto", a laundryman.