Working mechanism of Dunders:

Question

If we have an expression "x + y" and x is an instance of class K, then Python will check the class definition of K. If K has a method __add__ it will be called with x.__add__(y), otherwise we will get an error message.

class Vector2D:
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
def __add__(self, other):
return Vector2D(self.x + other.x, self.y + other.y, self.z + other.z)

first = Vector2D(5, 7, 8)
second = Vector2D(3, 9, 12)
result = first + second
print(result.x)
print(result.y)
print(result.z)

Output:
8
16
20

Answer 1

and if you implement __repr__ and __str__, you can see it in the interactive session and you can use print on it, respectively