英文文档：

hash(object)Return the hash value of the object (if it has one). Hash values are integers. They are used to quickly compare dictionary keys during a dictionary lookup. Numeric values that compare equal have the same hash value (even if they are of different types, as is the case for 1 and 1.0).

说明：　　

　　1. 返回对象的哈希值，用整数表示。哈希值在字典查找时，可用于快速比较键的值。

>>> hash('good good study')

1032709256

>>> 1.0 == 1

True

>>> hash(1.0)

1

>>> hash(1)

1

>>> hash(1.0000)

1