code: function formatter (options) {
    const line = [
      new Date().toISOString(),
      options.level
    ]
  
    if (options.message !== undefined) line.push(options.message)
  
    if (options.meta && Object.keys(options.meta).length) line.push(JSON.stringify(options.meta))
  
    return line.join(' ')
  }
docs: formats winston log lines
  @param {object} options - log info from winston
  @return {string} formatted log line