code: func (api *HandshakeAPI) GetHandshakeKeys(pubkeyid string, topic Topic, in bool, out bool) (keys []string, err error) {
  	if in {
  		for _, inkey := range api.ctrl.validKeys(pubkeyid, &topic, true) {
  			keys = append(keys, *inkey)
  		}
  	}
  	if out {
  		for _, outkey := range api.ctrl.validKeys(pubkeyid, &topic, false) {
  			keys = append(keys, *outkey)
  		}
  	}
  	return keys, nil
  }
docs: // Returns all valid symmetric keys in store per peer (public key)
  // and topic.
  //
  // The `in` and `out` parameters indicate for which direction(s)
  // symmetric keys will be returned.
  // If both are false, no keys (and no error) will be returned.