(logic) A logical fallacy consisting of providing one or more examples as a proof of a more general statement.

plural of proof by example

(transitive, idiomatic) To punish someone so as to give a warning to others.

to show the way or demonstrate a technique to individuals or a group by going ahead or doing something before the others

Synonym of textbook case

(transitive with for) to behave in a way that other people should.