Determine if Salesforce org is sandbox in case there's something you need to enable on sandboxes but not prod

OrgIsSandBoxClass.cls

@TestVisible
private static Boolean orgIsSandbox {
  get {
    if (orgIsSandbox == null) {
      orgIsSandbox = [SELECT IsSandbox FROM Organization LIMIT 1].IsSandbox;
    }
    return orgIsSandbox;
  }
  set;
}