code: func (cm *CheckManager) loadCACert() error {
  	if cm.certPool != nil {
  		return nil
  	}
  
  	cm.certPool = x509.NewCertPool()
  
  	var cert []byte
  	var err error
  
  	if cm.enabled {
  		// only attempt to retrieve broker CA cert if
  		// the check is being managed.
  		cert, err = cm.fetchCert()
  		if err != nil {
  			return err
  		}
  	}
  
  	if cert == nil {
  		cert = circonusCA
  	}
  
  	cm.certPool.AppendCertsFromPEM(cert)
  
  	return nil
  }
docs: // loadCACert loads the CA cert for the broker designated by the submission url