Ask HN: What's the Equivalent of 'Hello, World' for a Quantum Computer?

The 'Hello,World' program is one of the simplest programs to demonstrate how to go about writing a program in a new programming language.

What is an equivalent simple program which demonstrates how to write a very simple program for a quantum computer?

I have tried (and failed) to imagine such a program. Can somebody who has actually used a quantum computer show us an actual quantum computer program?