input: Write a function to convert a given temperature value from Fahrenheit to Celsius.
  def fahrenheit_to_celsius(temp):
      celsius = (temp - 32) * 5/9 
      return round(celsius, 2)
  
  assert fahrenheit_to_celsius(32) == 0.0
  assert fahrenheit_to_celsius(212) == 100.0
  assert fahrenheit_to_celsius(98.6) == 37.0
  assert fahrenheit_to_celsius(0) == -17.78
  assert fahrenheit_to_celsius(-40) == -40.0
output: def fahrenheit_to_celsius(temp):
      celsius = (temp - 32) * 5/9 
      return round(celsius, 2)