#!/usr/bin/env python
#coding:utf-8

from decimal import Decimal
a=Decimal('4.2')
b=Decimal('2.1')
print(a+b)
print((a+b)==Decimal('6.3'))

from decimal import localcontext

a=Decimal('1.3')
b=Decimal('1.7')
print(a/b)
with localcontext() as ctx:
    ctx.prec=3
    print(a/b)

with localcontext() as ctx:
    ctx.prec=50
    print(a/b)

    