code: func RandomG2(r io.Reader) (*big.Int, *G2, error) {
  	k, err := randomK(r)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	return k, new(G2).ScalarBaseMult(k), nil
  }
docs: // RandomG2 returns x and g₂ˣ where x is a random, non-zero number read from r.