input: def compare_values(a, b):
      """
      Write a function that accepts integers, floats, or strings representing
      real numbers, and returns the larger of the two inputs in their respective data type.
      Return None if the inputs are identical.
      Note: When a real number is expressed as a string, the decimal separator can be . or ,
  
      compare_values(1, 2.5) ➞ 2.5
      compare_values(1, "2,3") ➞ "2,3"
      compare_values("5,1", "6") ➞ "6"
      compare_values("1", 1) ➞ None
      """
output:     if isinstance(a, str):
          a = float(a.replace(',', '.'))
      if isinstance(b, str):
          b = float(b.replace(',', '.'))
  
      if a == b:
          return None
      return a if a > b else b