# A simple vector class

def vec(*v):

    return Vec(*v)

class Vec:

    def __init__(self, *v):

        self.v = list(v)

    def fromlist(self, v):

        if not isinstance(v, list):

            raise TypeError

        self.v = v[:]

        return self

    def __repr__(self):

        return 'vec(' + repr(self.v)[1:-1] + ')'

    def __len__(self):

        return len(self.v)

    def __getitem__(self, i):

        return self.v[i]

    def __add__(self, other):

        # Element-wise addition

        v = map(lambda x, y: x+y, self, other)

        return Vec().fromlist(v)

    def __sub__(self, other):

        # Element-wise subtraction

        v = map(lambda x, y: x-y, self, other)

        return Vec().fromlist(v)

    def __mul__(self, scalar):

        # Multiply by scalar

        v = map(lambda x: x*scalar, self.v)

        return Vec().fromlist(v)

def test():

    a = vec(1, 2, 3)

    b = vec(3, 2, 1)

    print a

    print b

    print a+b

    print a-b

    print a*3.0

test()