pythonで辞書を値で並べ替える

# coding=utf-8

d = {'john': 22, 'ringo': 22, 'paul': 20, 'george': 19}

# 昇順
assert sorted(d.items(), key=lambda x: x[1]) \
       == [('george', 19), ('paul', 20), ('ringo', 22), ('john', 22)]

# 降順
assert sorted(d.items(), key=lambda x: x[1], reverse=True) \
       == [('ringo', 22), ('john', 22), ('paul', 20), ('george', 19)]