python 快速创建字典 fromkes()

作用：快速创建字典

特点：共用value

seq = [\'google\', \'ie\', \'firefox\']
# seq为可迭代对象（str, list, tuple, dict, set）
dic = dict.fromkeys(seq)
print(dic)      # {\'google\': None, \'ie\': None, \'firefox\': None}

dic2 = dict.fromkeys(seq, 10)
print(dic2)     # {\'google\': 10, \'ie\': 10, \'firefox\': 10}