old_contents: #!/usr/bin/env python
  #Features as below:
  #1. Detect the battery's power left via ADC port.
  #2. Check the device on-line or off-line status by hbmqtt heartbeat.  
  
  
new_contents: #!/usr/bin/env python
  #Features as below:
  #1. Detect the battery's power left via ADC port.
  #2. Check the device on-line or off-line status by LoRa heartbeat.  
  
  
subject: Update dev_mag.py