error message with exception in cross product

Question

I'm trying to define a class Vector, in a way the cross-product of two vectors v1 and v2 results in a perpendicular unit vector v3, while such a product is zero, then it should turn back an exception message. I've set the code as follows:

  def __init__(self, x, y, z):   
    self.x = x
    self.y = y
    self.z = z

  def __repr__(self): 
    return "Vector(" + str(self.x) + ", " + str(self.y) + ", " + str(self.z) + ")"
  
  def cross(self, V):  
    return Vector(self.y * V.z - self.z * V.y,self.z * V.x - self.x * V.z,self.x * V.y - self.y * V.x)

  def find_axis(v,w):
        x = v.cross(w)
        print(type(x))
        if x==Vector(0,0,0):
            return "error"
    #raise Exception(" (ValueError)")return x

But when trying to run the product between vectors, which cross product would be supposed to be different from zero, like the following example:

v = Vector(1, 2, 3)
w = Vector(1, 2, 3)

And I get excalty:

v.cross(w)
Vector(0, 0, 0)

I cannot figure out which the error is, since in this case the code is supposed to return an error message. Can anyone please know what is up?

A second way I tried was

class Vector:

  def __init__(self, x, y, z):
    self.x = x
    self.y = y
    self.z = z

  def __repr__(self): 
    return "Vector(" + str(self.x) + ", " + str(self.y) + ", " + str(self.z) + ")"
        
  def cross(self, V):  
    return Vector(self.y * V.z - self.z * V.y,self.z * V.x - self.x * V.z,self.x * V.y - self.y * V.x)

  def __eq__(self, V):
        if self.x == V.x and self.y == V.y and self.z == V.z: 
            raise ValueError("negative x")

but I got the same problem

Answer 1

The solution to this just required to invert in the exact order the if statement unde cross definition:

class Vector:

  def __init__(self, x, y, z):
    self.x = x
    self.y = y
    self.z = z

  def __repr__(self): 
    return "Vector(" + str(self.x) + ", " + str(self.y) + ", " + str(self.z) + ")"
        
  def cross(self, V):
    if self.x == V.x and self.y == V.y and self.z == V.z: 
        raise ValueError("The vector is parallel and not perpendicular")
    else:    
        return Vector(self.y * V.z - self.z * V.y, self.z * V.x - self.x * V.z,self.x * V.y - self.y * V.x)

#1st case

v = Vector(1, 2, 3)
w = Vector(9, 2, 3)

print(v.cross(w))

#2nd Case

v = Vector(1, 2, 3)
w = Vector(1, 2, 3)

print(v.cross(w))