input: Write a python function to simulate a game of Rock, Paper, Scissors.
  assert rock_paper_scissors('rock', 'scissors') == 'You win!'
  assert rock_paper_scissors('paper', 'rock') == 'You win!'
  assert rock_paper_scissors('scissors', 'paper') == 'You win!'
  assert rock_paper_scissors('rock', 'rock') == 'It\'s a tie!'
  assert rock_paper_scissors('scissors', 'rock') == 'You lose!'
output: def rock_paper_scissors(player1, player2):
      if player1 == player2:
          return "It's a tie!"
      elif (player1 == 'rock' and player2 == 'scissors') or (player1 == 'scissors' and player2 == 'paper') or (player1 == 'paper' and player2 == 'rock'):
          return 'You win!'
      else:
          return 'You lose!'