code: def check(operations, loud=False):
      if not CHECKERS:
          load_checkers()
      roll_call = []
      everything_ok = True
      if loud and operations:
          title = "Preflyt Checklist"
          sys.stderr.write("{}\n{}\n".format(title, "=" * len(title)))
      for operation in operations:
          if operation.get('checker') not in CHECKERS:
              raise CheckerNotFoundError(operation)
          checker_cls = CHECKERS[operation['checker']]
          args = {k: v for k, v in operation.items() if k != 'checker'}
          checker = checker_cls(**args)
          success, message = checker.check()
          if not success:
              everything_ok = False
          roll_call.append({"check": operation, "success": success, "message": message})
          if loud:
              sys.stderr.write(" {}\n".format(pformat_check(success, operation, message)))
      return everything_ok, roll_call