code: func handleVerifyChain(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {
  	c := cmd.(*btcjson.VerifyChainCmd)
  
  	var checkLevel, checkDepth int32
  	if c.CheckLevel != nil {
  		checkLevel = *c.CheckLevel
  	}
  	if c.CheckDepth != nil {
  		checkDepth = *c.CheckDepth
  	}
  
  	err := verifyChain(s, checkLevel, checkDepth)
  	return err == nil, nil
  }
docs: // handleVerifyChain implements the verifychain command.