old_contents: # using strings as keys in dict
  
  d = {'1': 1, '2': 2}
  print(d['1'], d['2'])
  
  d['3'] = 3
  print(d['1'], d['2'], d['3'])
  
  d['2'] = 222
  print(d['1'], d['2'], d['3'])
  
new_contents: # using strings as keys in dict
  
  d = {'1': 1, '2': 2}
  print(d['1'], d['2'])
  
  d['3'] = 3
  print(d['1'], d['2'], d['3'])
  
  d['2'] = 222
  print(d['1'], d['2'], d['3'])
  
  d2 = dict(d)
  print('2' in d2)
  print(id(d) != id(d2), d == d2)
  
subject: Add combined test for dict(dict) and dict equality.