input: Write a python function to determine the winner of a Rock, Paper, Scissors game.
  assert determine_winner('R', 'S') == 'Player 1 wins!'
  assert determine_winner('S', 'R') == 'Player 2 wins!'
  assert determine_winner('P', 'R') == 'Player 1 wins!'
  assert determine_winner('R', 'P') == 'Player 2 wins!'
  assert determine_winner('S', 'P') == 'Player 1 wins!'
  assert determine_winner('P', 'S') == 'Player 2 wins!'
  assert determine_winner('R', 'R') == 'It\'s a tie!'
  assert determine_winner('P', 'P') == 'It\'s a tie!'
  assert determine_winner('S', 'S') == 'It\'s a tie!'
output: def determine_winner(player1, player2):
      if player1 == player2:
          return "It's a tie!"
      elif (player1 == 'R' and player2 == 'S') or (player1 == 'S' and player2 == 'P') or (player1 == 'P' and player2 == 'R'):
          return "Player 1 wins!"
      else:
          return "Player 2 wins!"