code: func NewBackend(cfg *Config, logger log.Logger) Backend {
  	conn, ptc, psc, err := newInstance(cfg, logger)
  	if err != nil {
  		logger.Fatal(err.Error())
  	}
  
  	b := &backendInstance{cfg: cfg, ptc: ptc, psc: psc,
  		conn: conn, logger: logger,
  	}
  
  	go b.connectionControl()
  
  	return b
  }
docs: // NewBackend returns eth back implementation.