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: 
  You can achieve some improvements using built-in `opam` commands.
  
  Using `opam install . --inplace-build --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 trigerring a full
  recompilation of your switch.
  
  You can also run `make install` manually, which will not trigger a
  
negative.code: opam install . --inplace-build
  -----
  
  However, if you 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.
  You will then need to install the compiler, either from the working directory
  (that you must build yourself) or using the regular sandboxed builds.
  
  -----
  # Example with regular opam build
  opam switch create . --empty
  opam install .
  ./configure --prefix=$(opam var prefix) # put extra configuration args here
  -----
  
  -----
  # Example with installation from the current directory, installing only the
  # bytecode versions of the tools
  opam switch create . --empty
  ./configure --prefix=$(opam var prefix) # put extra configuration args here
  make world && make opt
  opam install . --assume-built
  -----
  
  ===== Basic workflow
  