How to avoid adding duplicate keys to dictionary by mistake ...

There would be cases where large dictionaries are being embedded in the code (multiple pages in length) and users might append something to end of the dictionary, just assuming that its not already in the dictionary. 

This could be easily avoided by following dict() instead of {} notation for dictionaries.


  >>> a = {
  ...   'a': 1,
  ...   'b': 2,
  ...   'c': 3,
  ...   'd': 'nextpage',
  ...   'a': 0  ... }
  >>> print a
  {'a': 0, 'c': 3, 'b': 2, 'd': 'nextpage'}
  >>> a = dict(
  ...   a=1,
  ...   b=2,
  ...   c=3,
  ...   d='nextpage',
  ...   a=0
  ... )
    File "<stdin>", line 6  SyntaxError: keyword argument repeated

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