code: function generateId () {
      var now = Date.now()
      if (now <= this.lastTime) {
        now = this.lastTime
        this.sequence += 1
      } else {
        this.lastTime = now
        this.sequence = 0
      }
      return now + ' ' + this.nodeId + ' ' + this.sequence
    }
docs: Generate next unique action ID.
  
  @return {string} Unique action ID.
  
  @example
  const id = log.generateId()