lambda tuple sort

gistfile1.txt

In [20]: foo = [(3,8), (5,3), (4,6), (1,5), (4,3), (4,7)]

In [21]: sorted(foo)
Out[21]: [(1, 5), (3, 8), (4, 3), (4, 6), (4, 7), (5, 3)]

In [22]: sorted(foo, key=lambda _: (-_[0],_[1]))
Out[22]: [(5, 3), (4, 3), (4, 6), (4, 7), (3, 8), (1, 5)]

In [23]: sorted(foo, key=lambda X: (-X[0], X[1]))
Out[23]: [(5, 3), (4, 3), (4, 6), (4, 7), (3, 8), (1, 5)]

# No magic difference between _ and X, they're just scope variables.