hunk.code_window:       ['B', 'b', m],
         ['C', 'c', m],
       ]);
     });
     it('merges two maps', () => {
       const m1 = Map({ a: 'A', b: 'B', c: 'C' });
       const m2 = Map({ wow: 'OO', d: 'DD', b: 'BB' });
       expect(m2.toObject()).toEqual({ wow: 'OO', d: 'DD', b: 'BB' });
       const m3 = m1.merge(m2);
  
hunk.labels: keep keep keep keep add keep keep keep keep keep
hunk.after_edit:   it('has the same iterator function for entries', () => {
       const m = Map({ a: 'A', b: 'B', c: 'C' });
       expect(m[Symbol.iterator]).toBe(m.entries);
     });
  
hunk.file_path: __tests__/Map.ts
hunk.type: add
file: import arrCopy from './arrCopy';
  import hasOwnProperty from './hasOwnProperty';
  
  export default function shallowCopy(from) {
    if (Array.isArray(from)) {
      return arrCopy(from);
    }
    const to = {};
    for (const key in from) {
      if (hasOwnProperty.call(from, key)) {
        to[key] = from[key];
      }
    }
    return to;
  }
  