code: function IntervalMonitor(monitor, prefix, interval) {
    this.monitor = monitor;
    this.prefix = prefix || this.monitor.prefix;
    this.interval = interval || this.monitor.interval;
  }
docs: Abstract base class for all types of specialized monitors that report
  information periodically over a given interval.
  @param {monitor-dog.Monitor} Base monitor class for the interval monitor.
  @param {string} prefix Prefix to use for the interval monitor.
  @param {number} interval Amount of time between reports, in milliseconds.