let vcftools =   Installable_tool.make Machine.Tool.Default.vcftools     ~url:"http://downloads.sourceforge.net/project/vcftools/vcftools_0.1.12b.tar.gz"     ~install_program:(fun ~path -> KEDSL.Program.(         sh "make"         && shf  "cp -r bin %s" path         && shf  "cp -r lib/perl5/site_perl %s" path       ))     ~witness:(witness_file @@ "bin" // "vcftools")     ~init_program:(fun ~path ->         KEDSL.Program.(shf "export PATH=%s/bin/:$PATH" path                        && shf "export PERL5LIB=$PERL5LIB:%s/site_perl/" path))