title: How to prevent high level message to log into all low level message in winston?
body: <p>I am new to use winston library and I am facing problem that inspite of using different transport for error, info, warn I am unable to log error , info and warn message in separate files as defined in code. It logs higher level message in each lower level message like it logs error message in all error, info, warn and debug files. So please help me.</p>
  
  <pre><code>import { createLogger, format, transports } from 'winston'
  
  //setup logger
  const { combine, timestamp, json, colorize, simple } = format;
  const logger = createLogger({
    level: 'info',
    format: combine(
      timestamp({
        format: 'YYYY-MM-DD HH:mm:ss'
      }),
      json(),
    ),
    defaultMeta: { service: 'user-service' },
    transports: [
      new transports.Console({
        format: combine(colorize(), simple())
      }),
      new transports.File({
        filename: 'logs/error.log',
        level: 'error'
      }),
      new transports.File({
        filename: 'logs/warn.log',
        level: 'warn'
      }),
      new transports.File({
        filename: 'logs/info.log',
        level: 'info'
      }),
      new transports.File({
        filename: 'logs/debug.log',
        level: 'debug'
    })
    ]
  });
  
  logger.error('This is an error test message');
  logger.info('This is an info test message');
  logger.debug('This is a debug test message');
  
  </code></pre>