old_contents: # functions related to the board - http://docs.micropython.org/en/latest/esp8266/library/machine.html
  import machine
  import time
  
  # Define pin 2 as output
  # There id build-in LED on pin 2, use ESP8266 GPIO pin numbers
  # https://www.wemos.cc/product/d1-mini-pro.html
  pin = machine.Pin(2, machine.Pin.OUT)
  
  while True:
      # Set high voltage on pin
      pin.value(1);
      time.sleep(0.5)
      # Set low voltage on pin
      pin.value(0);
      time.sleep(0.5)
new_contents: # functions related to the board - http://docs.micropython.org/en/latest/esp8266/library/machine.html
  import machine
  import time
  
  # Define pin 2 as output
  # There id build-in LED on pin 2, use ESP8266 GPIO pin numbers
  # https://www.wemos.cc/product/d1-mini-pro.html
  pin = machine.Pin(2, machine.Pin.OUT)
  
  while True:
      # Set high voltage on pin
      pin.value(1)
      time.sleep(0.5)
      # Set low voltage on pin
      pin.value(0)
      time.sleep(0.5)
  
subject: Remove semicolon