这是该
decimal包中的“真实世界”示例：
>>> from decimal import Decimal>>> obj = Decimal('3.1415926535897932384626433832795028841971')>>> +obj != obj # The __pos__ function rounds back to normal precisionTrue>>> objDecimal('3.1415926535897932384626433832795028841971')>>> +objDecimal('3.141592653589793238462643383')
