code: func (k *Kite) AuthenticateFromKiteKey(r *Request) error {
  	claims := &kitekey.KiteClaims{}
  
  	token, err := jwt.ParseWithClaims(r.Auth.Key, claims, k.verify)
  	if err != nil {
  		return err
  	}
  
  	if !token.Valid {
  		return errors.New("Invalid signature in kite key")
  	}
  
  	if claims.Subject == "" {
  		return errors.New("token has no username")
  	}
  
  	r.Username = claims.Subject
  
  	return nil
  }
docs: // AuthenticateFromKiteKey authenticates user from kite key.