Vector class from Python tuple.

vec.py

class Vec(tuple):
    def __new__(cls, x, y=None, z=None):
        if y is None:
            return super(Vec, cls).__new__(cls, x)
        if z is None:
            return super(Vec, cls).__new__(cls, (x, y))
        return super(Vec, cls).__new__(cls, (x, y, z))
    def dot(self, other):
        return sum(x0 * x1 for (x0, x1) in zip(self, other))
    def __add__(self, other):
        return Vec(x0 + x1 for (x0, x1) in zip(self, other))
    def __sub__(self, other):
        return Vec(x0 - x1 for (x0, x1) in zip(self, other))
    def __mul__(self, other):
        if isinstance(other, (int, float)):
            return Vec(other * x0 for x0 in self)
        return Vec(x0 * x1 for (x0, x1) in zip(self, other))
    def __rmul__(self, other):
        return self.__mul__(other)

v = Vec(1, 2) + Vec(2, 1)
v += Vec(0, 1)
v *= 3

print(2 * v, v.dot(v))