anchor.diff:  command instead of the package-supplied one. It can be installed following
   instructions https://gitlab.ocamlpro.com/louis/opam-custom-install[here].
   
  -In our case, we need to build the compiler (to some extent, more details later),
  -then we run `opam custom-install . -- make install`.
  +In our case, we need to build the compiler, and when we've built everything
  +that we need then we run `opam custom-install ocaml-variants -- make install`.
   This will make `opam` remove the previously installed version of the compiler
   (if any), then install the new one in its stead.
  +
  +-----
  +# reinstall the compiler, and rebuild all opam packages
  +opam custom-install ocaml-variants -- make install
  +-----
   
   Since most `opam` packages depend on the compiler, this will trigger a
   reinstallation of all the packages in the switch.
  
positive.code: opam install . --inplace-build
  -----
  
  However, if you want to avoid the initial full compilation or need specific
  configuration options, you can also configure it manually, as long as you make
  sure that the configuration prefix is the one where `opam` would install the
  compiler.
  For instance, if you don't need `ocamldoc` and `ocamltest` you can run:
  
  -----
  opam switch create . --empty
  ./configure --prefix=$(opam var prefix) --disable-ocamldoc --disable-ocamltest
  -----
  
  ===== Basic workflow
  
negative.code: 
  You can achieve some improvements using built-in `opam` commands.
  
  Using `opam install . --assume-built` will simply remove the
  package for the compiler, then run the installation instructions
  (`make install`) in the working directory, tracking the installed files
  correctly. The main difference with the `opam-custom-install` version
  is that there's no way to prevent this command from triggering a full
  recompilation of your switch.
  
  You can also run `make install` manually, which will not trigger a
  