let strelka =   let url =     "ftp://strelka:%27%27@ftp.illumina.com/v1-branch/v1.0.14/strelka_workflow-1.0.14.tar.gz" in   let strelka_bin = "usr" // "bin" in   let witness = witness_file @@ strelka_bin // "configureStrelkaWorkflow.pl" in   let install_program ~path =     (* C.f. ftp://ftp.illumina.com/v1-branch/v1.0.14/README *)     KEDSL.Program.(       shf "./configure --prefix=%s" (path // "usr")       && sh "make && make install"     )   in   let init_program ~path =     KEDSL.Program.(shf "export STRELKA_BIN=%s/%s" path strelka_bin) in   Installable_tool.make Machine.Tool.Default.strelka ~url     ~init_program ~install_program ~witness