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curriculum/challenges/english/blocks/learn-special-methods-by-building-a-vector-space/66680ddfd0f8c76782923cb0.md

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--description--

The norm() method is returning the correct values, but there's still something you can improve: readability.

The vars() built-in function takes an object as its argument and returns the __dict__ attribute of that object.

Instead of directly accessing the __dict__ attribute of self, modify the norm method to use the vars() function.

--hints--

You should modify your norm method to use vars(self) instead of self.__dict__.

js
({ test: () => assert(runPython(`_Node(_code).find_class("R2Vector").find_function("norm").has_return("sum(val**2 for val in vars(self).values())**0.5")`)) })

--seed--

--seed-contents--

py

class R2Vector:
    def __init__(self, *, x, y):
        self.x = x
        self.y = y
--fcc-editable-region--
    def norm(self):
        return sum(val**2 for val in self.__dict__.values())**0.5
--fcc-editable-region--
    def __str__(self):
        return f'{self.x, self.y}'

class R3Vector(R2Vector):
    def __init__(self, *, x, y, z):
        super().__init__(x=x, y=y)
        self.z = z

v1 = R2Vector(x=2, y=3)
v2 = R3Vector(x=2, y=2, z=3)
print(v1.norm())
print(v2.norm())