input: Write a python function to eliminate duplicate elements in a tuple and substitute those duplicates with a specified value.
  assert replace_duplicates((1, 1, 4, 4, 4, 5, 5, 6, 7, 7)) == (1, 'MSP', 4, 'MSP', 'MSP', 5, 'MSP', 6, 7, 'MSP')
  assert replace_duplicates((2, 3, 4, 4, 5, 6, 6, 7, 8, 9, 9)) == (2, 3, 4, 'MSP', 5, 6, 'MSP', 7, 8, 9, 'MSP')
  assert replace_duplicates((2, 2, 5, 4, 5, 7, 5, 6, 7, 7)) == (2, 'MSP', 5, 4, 'MSP', 7, 'MSP', 6, 'MSP', 'MSP')
output: def replace_duplicates(tpl):
      seen = set()
      result = []
      for item in tpl:
          if item in seen:
              result.append('MSP')
          else:
              seen.add(item)
              result.append(item)
      return tuple(result)