code: func (p *BlockPuller) probeEndpoint(endpoint string, minRequestedSequence uint64) (*endpointInfo, error) {
  	conn, err := p.Dialer.Dial(endpoint)
  	if err != nil {
  		p.Logger.Warningf("Failed connecting to %s: %v", endpoint, err)
  		return nil, err
  	}
  
  	lastBlockSeq, err := p.fetchLastBlockSeq(minRequestedSequence, endpoint, conn)
  	if err != nil {
  		conn.Close()
  		return nil, err
  	}
  
  	return &endpointInfo{conn: conn, lastBlockSeq: lastBlockSeq, endpoint: endpoint}, nil
  }
docs: // probeEndpoint returns a gRPC connection and the latest block sequence of an endpoint with the given
  // requires minimum sequence, or error if something goes wrong.