Python 2.7 Python 2.7中的分数值运算

我想做一个程序，在这个程序中分数值可以进行数学运算。 我已经编写了一个代码，但它显示了一个错误

TypeError：两个参数都应该是有理实例。

print "We'll ask you for two fraction values."
print "After taking values from you, we'll use python built in operaters to make it happen."

from fractions import *
value_1_one = raw_input("Please enter 1st value : ")

value_1_two = raw_input("Please enter 1st two value : ")

value_2_one = raw_input("Please enter 2nd one value.")

value_2_two = raw_input("Please enter 2nd two value.")

vaule_1 = Fraction(value_1_one, value_1_two)
value_2 = Fraction(value_2_one, value_2_two)
print "We have %i and %i as values." % (value_one, value_two)
print "What kind of operation you would like to make."
print "Like Add, Sub, Multi, Devide"

op_kind = raw_input(">>>")
if "Add" in op_kind:
    print (value_1 + value_2)
elif "Sub" in op_kind:
    print (value_1 - value_2)
elif "Multi" in op_kind:
    print (value_1 * value_2)
elif "Devide" in op_kind:
    print (value_1 / value_2)
else:
    print "Ask Mr. Ramanuj for further details."

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raw\u input（）

始终返回字符串<代码>分数（）需要整数（或其他有理数）。谢谢！，我可以像这样在cmd中输入，21/34在一行中。