input: Write a function to simulate a rock-paper-scissors game between two players. The function should return the result of the game based on the choices made by the two players. If the choices of both players are the same, it should return 'It is a draw!'. If player 1 wins, it should return 'Player 1 wins!'. If player 2 wins, it should return 'Player 2 wins!'.
  assert play_game('rock', 'scissors')=='Player 1 wins!'
  assert play_game('paper', 'scissors')=='Player 2 wins!'
  assert play_game('rock', 'rock')=='It is a draw!'
  assert play_game('scissors', 'paper')=='Player 1 wins!'
  assert play_game('paper', 'rock')=='Player 1 wins!'
output: def play_game(player1, player2):
      if player1 == player2:
          return 'It is a draw!'
      elif (player1 == 'rock' and player2 == 'scissors') or (player1 == 'scissors' and player2 == 'paper') or (player1 == 'paper' and player2 == 'rock'):
          return 'Player 1 wins!'
      else:
          return 'Player 2 wins!'