new_contents: def example_1():
      a = { 'x': 1, 'y': 2, 'z': 3 }
      b = { 'w': 10, 'x': 11, 'y': 2 }
  
      print(a.keys() & b.keys())
      print(a.keys() - b.keys())
      print(a.items() & b.items())
  
      c = { key:a[key] for key in a.keys() - { 'z', 'w' } }
      print(c)
  
  
  if __name__ == '__main__':
      example_1()
  
subject: add data for recipe 1.9