let kallisto =
  let url = "https://github.com/pachterlab/kallisto/releases/download/v0.42.3/kallisto_linux-v0.42.3.tar.gz" in
  installable_tool Machine.Tool.Default.kallisto ~url
    ~witness:(witness_file "kallisto")
    ~install_program:KEDSL.Program.(fun ~path ->
        shf "cp -r * %s" path
      )
  ~init_program:add_to_dollar_path