docs: def vee_map(skew):
      """Return the vee map of a vector
  
      """
  
      vec = 1/2 * np.array([skew[2,1] - skew[1,2],
                            skew[0,2] - skew[2,0],
                            skew[1,0] - skew[0,1]])
  
      return vec