This method will be invoked to perform the “`+`

” operator whenever a `Rational`

instance appears on the left side of
that operator. To simplify life, we assume here that the
operand on the right side is also a `Rational`

instance.

Basically, what we are doing is adding two fractions. Here is the algebraic rule for adding fractions:

In this method, `self`

is the left-hand
operand and `other`

is the right-hand
operand.

rational.py

def __add__ ( self, other ): """Add two rational numbers. """ return Rational ( self.n * other.d + other.n * self.d, self.d * other.d )