input: Write a function to convert a given temperature value from Fahrenheit to Celsius. If the given temperature is below absolute zero (which is -459.67 in Fahrenheit) then return "Invalid". Round the result to 2 decimal places.
  assert fahrenheit_to_celsius(32)==0.0
  assert fahrenheit_to_celsius(212)==100.0
  assert fahrenheit_to_celsius(50)==10.0
  assert fahrenheit_to_celsius(-500)=="Invalid"
output: def fahrenheit_to_celsius(fahrenheit):
      if fahrenheit < -459.67:
          return "Invalid"
      celsius = (fahrenheit - 32) * 5 / 9
      return round(celsius, 2)