code: function typescriptSource() {
      return gulp.src([
          "./src/helper/*.ts",
          "./src/BasicCollection.ts",
          "./src/OrderedCollection.ts",
          "./src/CollectionStatic.ts",
          "./src/internal/Collection.ts",
          "./src/internal/MinHeap.ts",
          "./src/internal/OrderedCollection.ts",
          "./src/module.ts"
      ])
  
          // remove import statements
          .pipe(replace(/import\s[^;]+;/ig, ""))
  
          // remove exports for hidden internal stuff starting with two "_",
          // exports with just one "_" remain as they are required for testing
          .pipe(replace(/export\s(\w+\s__)/ig, "$1"))
          .pipe(concat("linq.ts"))
          .pipe(gulp.dest("./build"));
  }
docs: /*
  Merge sources