text: /**
   * Public: test function to filter out malformed packets
   *
   * Parameters:
   *
   *   fields - Array of packet data (e.g. [ '100', 'ms', '@0.1' ])
   *
   * Returns true for a valid packet and false otherwise
   */
  function isNumber(str) {
      return Boolean(str && !isNaN(str));
  }
  
  function isValidSampleRate(str) {
      var validSampleRate = false;
      if(str.length > 1 && str[0] === '@') {
          var numberStr = str.substring(1);
          validSampleRate = isNumber(numberStr) && numberStr[0] != '-';
      }
      return validSampleRate;
  }
  
  function is_valid_packet(fields) {
  
      // test for existing metrics type
      if (fields[1] === undefined) {
          return false;
      }
  
      // filter out malformed sample rates
      if(fields[2] !== undefined) {
          if(!isValidSampleRate(fields[2])) {
              return false;
          }
      }
  
      // filter out invalid metrics values
      switch(fields[1]) {
          case 's':
              return true;
          case 'g':
              return isNumber(fields[0]);
          case 'ms':
              return isNumber(fields[0]) && Number(fields[0]) >= 0;
          default:
              if (!isNumber(fields[0])) {
                  return false;
              }
              return true;
      }
  
  }
  
  exports.is_valid_packet = is_valid_packet;
  
  exports.writeConfig = function(config, stream) {
    stream.write("\n");
    for (var prop in config) {
      if (!config.hasOwnProperty(prop)) {
        continue;
      }
      if (typeof config[prop] !== 'object') {
        stream.write(prop + ": " + config[prop] + "\n");
        continue;
      }
      var subconfig = config[prop];
      for (var subprop in subconfig) {
        if (!subconfig.hasOwnProperty(subprop)) {
          continue;
        }
        stream.write(prop + " > " + subprop + ": " + subconfig[subprop] + "\n");
      }
    }
  };
  