anchor.diff:      try
           sh(within_container(Name, fetch(archive_url(GitRef), archive_file(GitRef)))),
           sh(within_container(Name, extract(archive_file(GitRef)))),
  -        ct:pal("last result: ~p", [sh(within_container(Name, ["ls ", repo_dir(GitRef)]))]),
  -        ct:fail("not implemented yet")
  +        sh(within_container(Name, install(repo_dir(GitRef)))),
  +        sh(within_container(Name, file_exists("$HOME/.erlang"))),
  +        sh(within_container(Name, file_exists("$HOME/.erlang.d/user_default.erl"))),
  +        sh(within_container(Name, file_exists("$HOME/.erlang.d/user_default.beam"))),
  +        sh(within_container(Name, docsh_works()))
       after
           sh("docker stop " ++ Name)
       end.
  
positive.code: 
  sh(Command) when is_binary(Command) -> sh([Command]);
  sh(Command) ->
      {done, 0, _} = erlsh:oneliner(?b2l(?il2b(Command))).
  
  start_container(Name, Args) ->
      Fdlink = erlsh:fdlink_executable(),
  
negative.code: 
  repo_dir(GitReference) ->
      ["docsh-", GitReference].
  
  install(RepoDir) ->
      ["cd ", RepoDir, "; ./install.sh"].
  
  file_exists(File) ->
      ["file -E ", File].
  
  docsh_works() ->
      ["erl -noinput -noshell -eval 'erlang:display(docsh:module_info(module)).' -s erlang halt"].
  