Compute dot product of two vectors without using extra libraries

Question

I would like to write a function to compute the dot product of two vectors without using extra libraries. Following is an attempt that I made. Can someone point out the flaws in

Answer 1

def dot(v1,v2):
    if len(v1) != len(v2):
        raise ValueError
    return sum(i1*i2 for i1,i2 in zip(v1,v2))