title: why does appending to list in dictonary have different results?
body: <p><em>Python 3.7.6 (default, Jan  8 2020, 20:23:39) [MSC v.1916 64 bit (AMD64)]</em></p>
  
  <pre><code>my_list = ["a","b","c"]
  
  dict_one = {key:[] for key in my_list}
  print(dict_one)
  {'a': [], 'b': [], 'c': []}
  
  dict_two = dict.fromkeys(my_list, [])
  print(dict_two)
  {'a': [], 'b': [], 'c': []}
  
  dict_one['a'].append('some_data')
  dict_two['a'].append('some_data')
  
  print(dict_one)
  {'a': ['some_data'], 'b': [], 'c': []}
  
  print(dict_two)
  {'a': ['some_data'], 'b': ['some_data'], 'c': ['some_data']}
  </code></pre>
  
  <p>I excpected the same result for dict_one and dict_two.
  Could anyone please explain the difference ?</p>