input: def compare_values(x, y):
      """
      Write a function that accepts integers, floats, or strings symbolizing
      real numbers, and yields the larger value based on its type.
      Return None if the values are identical.
      Note: Real numbers may have a decimal as . or , if represented as a string.
  
      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(x, str):
          x = x.replace(',', '.')
      if isinstance(y, str):
          y = y.replace(',', '.')
  
      try:
          num_x = float(x)
      except ValueError:
          num_x = x
  
      try:
          num_y = float(y)
      except ValueError:
          num_y = y
  
      if num_x == num_y:
          return None
      return x if num_x > num_y else y
  