Common mathematical set operations are supported.

For A = {'a','b','c','d'} and B = {'c','d','e','f'}:

- A.intersection(B) is {'c','d'}; shorthand:A & B

- A.union(B) is {'a','b','c','d'}; shorthand: {A | B}

- A.difference(B) is {'a','b'}; shorthand:A - B

- A.symmetric difference(B) is {'a','b','e','f'}; shorthand: AB

- A.issubset(B) is False; shorthand:A <= B

- A.issuperset(B) is False; shorthand:A >= B

Read a text from the input file infile.txt. Using list and sets find the unique words in that text.