code: func getFontKey(familyStr, styleStr string) string {
  	familyStr = strings.ToLower(familyStr)
  	styleStr = strings.ToUpper(styleStr)
  	if styleStr == "IB" {
  		styleStr = "BI"
  	}
  	return familyStr + styleStr
  }
docs: // getFontKey is used by AddFontFromReader and GetFontDesc