let bedtools =   Installable_tool.make Machine.Tool.Default.bedtools     ~url:"https://github.com/arq5x/bedtools2/archive/v2.23.0.tar.gz"     ~install_program:(fun ~path -> KEDSL.Program.(         sh "make" && shf "cp -r bin %s" path))     ~init_program:(fun ~path ->         KEDSL.Program.(shf "export PATH=%s/bin/:$PATH" path))     ~witness:(witness_file @@ "bin" // "bedtools")