"""
 vector.py
 
          |    . A = (x1,y1)
          |
    ------+------
          |
          |        . B = (x2,y2)

   A + B using vector addition (x1+x2, y1+y2)
 
"""

class Vector:
    
    def __init__(self, x,y):
        self.x = x
        self.y = y
        
    def __str__(self):
        return f"Vector({self.x}, {self.y})"

    def __add__(self, other):
        # v1 + v2 turns into v1.add(v2) if they are Vectors
        # and this Vector.__add__(v1, v2) implements that.
        return Vector( self.x + other.x, self.y + other.y )

def main():
    a = Vector(1, 2)
    print("A is ", a)
    b = Vector(10, 20)
    print("B is ", b)
    c = a + b
    print("C is ", c)

if __name__ == '__main__':
    main()