python - Make an overloaded operator use an argument -

let's suppose have simple class defines rational number:

class rational(object):     def __init__(self, numerator, denominator):          self.n = numerator         self.d = denominator      def gcd(self):         = self.n         b = self.d         while b:             a, b = b, % b         return      def simplify(self):         gcd = self.gcd()         self.n = self.n / gcd         self.d = self.d / gcd      def __add__(self, other):         rat = rational(self.n * other.d + self.d * other.n, self.d * other.d)         rat.simplify()         return rat 

now, whenever sum 2 rational instances, rational(2,3) + rational(1,3), method __add__ automatically simplifies number (returns rational(1,1)). like

        def __add__(self, other, simp=true):         rat = rational(self.n * other.d + self.d * other.n, self.d * other.d)         if simp:             rat.simplify()         return rat 

and able rational(2,3) +(0) rational(1,3) returns rational(3,3) , of course rational(2,3) + rational(1,3) should yield rational(1,1).