docs: def missing_vars(template_vars, parsed_content, obj):
      """If we find missing variables when rendering a template
      we want to give the user a friendly error"""
      missing = []
      default_vars = grok_vars(parsed_content)
      for var in template_vars:
          if var not in default_vars and var not in obj:
              missing.append(var)
  
      if missing:
          e_msg = "Missing required variables %s" % \
                  ','.join(missing)
          raise aomi_excep.AomiData(e_msg)