code: def cross(self, v):
          
          n = self.__class__()
          n.x = self.y * v.z - self.z * v.y
          n.y = - (self.x * v.z - self.z * v.x)
          n.z = self.x * v.y - self.y * v.x
  
          return n
docs: Cross product of two vectors.
  
          Parameters
          ----------
          v : CartesianVector
              The vector to take cross product with.
  
          Returns
          -------
          v : CartesianVector
              Cross product of this vector and the given vector.