code: func (set RoleSet) CertificateFormat() string {
  	var formats []string
  
  	for _, role := range set {
  		// get the certificate format for each individual role. if a role does not
  		// have a certificate format (like implicit roles) skip over it
  		certificateFormat := role.GetOptions().CertificateFormat
  		if certificateFormat == "" {
  			continue
  		}
  
  		formats = append(formats, certificateFormat)
  	}
  
  	// if no formats were found, return standard
  	if len(formats) == 0 {
  		return teleport.CertificateFormatStandard
  	}
  
  	// sort the slice so the most permissive is the first element
  	sort.Slice(formats, func(i, j int) bool {
  		return certificatePriority(formats[i]) < certificatePriority(formats[j])
  	})
  
  	return formats[0]
  }
docs: // CertificateFormat returns the most permissive certificate format in a
  // RoleSet.