Dr. Racket Homework:
Please submit these all in one file. These should all be functions that are no more than a few lines.
Simple function definitions
  1.Write a function Celsius->Kelvin which takes in a number of degrees Celsius 
  and returns the corresponding temperature in Kelvin. (Kelvin degrees are the 
  same size as Celsius degrees, but 0 Kelvin is approximately -273.15 Celsius.)
  2.Write a function Fahrenheit->Celsius which takes in a number of degrees 
  Fahrenheit and returns the corresponding temperature in Celsius. (The formula 
  is C = (F-32) * 5/9.)
  3.Write a function Fahrenheit->Kelvin which does what it sounds like.
Hint: you should be able to write this function with no numbers or arithmetic operators in the function body, by re-using previously-written functions.
credited to : Dr. Stephen Bloch