DSU: Decorate Sort Undecorate

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In Perl it is called Schwartzian transform

examples/lists/sort_dsu.py

animals = ['chicken', 'cow', 'snail', 'elephant']
print(sorted(animals))
print(sorted(animals, key=len))

decorated = [(len(w), w) for w in animals]
print(decorated)

decorated.sort()
result = [ d[1] for d in decorated]
print(result)

# at once
print( [ d[1] for d in sorted( [(len(w), w) for w in animals] ) ] )

['chicken', 'cow', 'elephant', 'snail']
['cow', 'snail', 'chicken', 'elephant']
[(7, 'chicken'), (3, 'cow'), (5, 'snail'), (8, 'elephant')]
['cow', 'snail', 'chicken', 'elephant']
['cow', 'snail', 'chicken', 'elephant']