python

inv dict(d) input: dictionary d representing an invertible function f output: dictionary representing the inverse of f, the returned dictionarys keys are the values of d and its values are the keys of d.

example: given an English-French dictionary {'thank you': 'merci', 'goodbye': 'au revoir'} return a French-English dictionary {'merci':'thank you', 'au revoir':'goodbye'}

>>> inv_dict({'goodbye': 'au revoir', 'thank you': 'merci'}) == {'merci':'thank you', 'au revoir':'goodbye'}