Gulp forking a stream (e.g. send different files to different dests)

gulp.fork.js

gulp.task("ts", function() {
  // These would be the names of two source files for example  
  tsRootFiles = ["rab", "buildRab"];

    tsRootFiles.forEach(tsFile => {
        let stream = gulp
            .src(`ts/${tsFile}.ts`)
            .pipe(sourcemaps.init())
            .pipe(
                ts({
                    noImplicitAny: true,
                    outFile: `${tsFile}.js`,
                    allowJs: true,
                    lib: ["ES2016"],
                    target: "ES5",
                })
            )
            .pipe(sourcemaps.write());
        // Now send them different places (here based on name but obvs. whatever logic suits)
        if (tsFile === "rab") {
            stream = stream.pipe(gulp.dest("_build/js"));
        } else {
            stream = stream.pipe(gulp.dest("banners/js"));
        }

        return stream;
    });
});