docs: function loadEnvFromFile (fileName) {
    try {
      var receivers = fs.readFileSync(fileName).toString()
      if (receivers) {
        var lines = receivers.split('\n')
      }
      if (/logsene-js/.test(process.env.DEBUG)) {
        console.log(new Date(), 'loading Sematext receiver URLs from ' + fileName)
      }
      lines.forEach(function (line) {
        var kv = line.split('=')
        if (kv.length === 2 && kv[1].length > 0) {
          process.env[kv[0].trim()] = kv[1].trim()
          if (/logsene-js/.test(process.env.DEBUG)) {
            console.log(kv[0].trim() + ' = ' + kv[1].trim())
          }
        }
      })
    } catch (error) {
      // ignore missing file or wrong format
      if (/logsene-js/.test(process.env.DEBUG)) {
        console.error(error.message)
      }
    }
  }