code: func Client(conn io.ReadWriteCloser, config *Config) (*Session, error) {
  	if config == nil {
  		config = DefaultConfig()
  	}
  
  	if err := VerifyConfig(config); err != nil {
  		return nil, err
  	}
  	return newSession(config, conn, true), nil
  }
docs: // Client is used to initialize a new client-side connection.
  // There must be at most one client-side connection.