code: func (key *Key) MonaxKeysJSON() string {
  	jsonKey := plainKeyJSON{
  		Address:    key.Address.String(),
  		Type:       "ed25519",
  		PrivateKey: PrivateKeyplainKeyJSON{Plain: key.PrivateKey},
  	}
  	bs, err := json.Marshal(jsonKey)
  	if err != nil {
  		return errors.Wrap(err, "could not create monax key json").Error()
  	}
  	return string(bs)
  }
docs: // Returns JSON string compatible with that stored by monax-keys