This project is called =hello_world=. It defines one library called
=hello_world= and one executable called =hello_world=.

The library is defined in =lib= and the executable in =bin=. It also
defines a test in =test=.

At the toplevel of the project, there is a =hello_world.opam=
file. This file is required so that =dune= knows that this is the
=hello_world= project.

To build everything that is meant to be installed in this project,
type:

#+begin_src
$ dune build @install
#+end_src

To run the tests, type:

#+begin_src
$ dune runtest
#+end_src
