code: def fields_exist(self, fields):
          '''
          Check existence of a list fields in exif
          '''
          for rexif in fields:
              vflag = False
              for subrexif in rexif:
                  if subrexif in self.tags:
                      vflag = True
              if not vflag:
                  print("Missing required EXIF tag: {0} for image {1}".format(
                      rexif[0], self.filename))
                  return False
          return Truf fields_exist(self, fields):
          '''
          Check existence of a list fields in exif
          '''
          for rexif in fields:
              vflag = False
              for subrexif in rexif:
                  if subrexif in self.tags:
                      vflag = True
              if not vflag:
                  print("Missing required EXIF tag: {0} for image {1}".format(
                      rexif[0], self.filename))
                  return False
          return True
docs: Check existence of a list fields in exif