hunk.code_window:       [3, 3, s],
       ]);
     });
     it('unions two sets', () => {
       const s1 = Set.of('a', 'b', 'c');
       const s2 = Set.of('d', 'b', 'wow');
       const s3 = s1.union(s2);
       expect(s3.toArray()).toEqual(['a', 'b', 'c', 'd', 'wow']);
  
hunk.labels: keep keep keep add keep keep keep keep keep
hunk.after_edit:   it('has the same iterator function for keys and values', () => {
       const s = Set([1, 2, 3]);
       expect(s[Symbol.iterator]).toBe(s.keys);
       expect(s[Symbol.iterator]).toBe(s.values);
     });
  
hunk.file_path: __tests__/Set.ts
hunk.type: add
file: {
    "compilerOptions": {
      "target": "es2015",
      "module": "commonjs",
      "sourceMap": true,
      "noImplicitAny": true,
      "noImplicitThis": true,
      "strictNullChecks": true,
      "strictFunctionTypes": true,
      "lib": ["es2015"],
      "types": []
    },
    "files": ["immutable.d.ts"]
  }
  