code: def cross_product(x1, y1, z1, x2, y2, z2):
      
      x = y1*z2 - y2*z1
      y = z1*x2 - x1*z2
      z = x1*y2 - y1*x2
      return x, y, z
docs: Cross product of two vectors, v1 x v2
      
      Parameters
      ----------
      x1 : float or array-like
          X component of vector 1
      y1 : float or array-like
          Y component of vector 1
      z1 : float or array-like
          Z component of vector 1
      x2 : float or array-like
          X component of vector 2
      y2 : float or array-like
          Y component of vector 2
      z2 : float or array-like
          Z component of vector 2
          
      Returns
      -------
      x, y, z
          Unit vector x,y,z components